全文获取类型
收费全文 | 11006篇 |
免费 | 510篇 |
国内免费 | 49篇 |
专业分类
耳鼻咽喉 | 172篇 |
儿科学 | 237篇 |
妇产科学 | 100篇 |
基础医学 | 1345篇 |
口腔科学 | 346篇 |
临床医学 | 665篇 |
内科学 | 2679篇 |
皮肤病学 | 172篇 |
神经病学 | 773篇 |
特种医学 | 573篇 |
外科学 | 1932篇 |
综合类 | 46篇 |
一般理论 | 4篇 |
预防医学 | 219篇 |
眼科学 | 188篇 |
药学 | 717篇 |
中国医学 | 22篇 |
肿瘤学 | 1375篇 |
出版年
2023年 | 45篇 |
2022年 | 93篇 |
2021年 | 154篇 |
2020年 | 70篇 |
2019年 | 132篇 |
2018年 | 204篇 |
2017年 | 186篇 |
2016年 | 227篇 |
2015年 | 214篇 |
2014年 | 290篇 |
2013年 | 365篇 |
2012年 | 589篇 |
2011年 | 703篇 |
2010年 | 381篇 |
2009年 | 394篇 |
2008年 | 646篇 |
2007年 | 699篇 |
2006年 | 721篇 |
2005年 | 686篇 |
2004年 | 718篇 |
2003年 | 660篇 |
2002年 | 639篇 |
2001年 | 158篇 |
2000年 | 147篇 |
1999年 | 189篇 |
1998年 | 183篇 |
1997年 | 178篇 |
1996年 | 166篇 |
1995年 | 121篇 |
1994年 | 129篇 |
1993年 | 132篇 |
1992年 | 101篇 |
1991年 | 123篇 |
1990年 | 96篇 |
1989年 | 99篇 |
1988年 | 86篇 |
1987年 | 71篇 |
1986年 | 68篇 |
1985年 | 64篇 |
1984年 | 72篇 |
1983年 | 71篇 |
1982年 | 53篇 |
1981年 | 46篇 |
1980年 | 33篇 |
1979年 | 32篇 |
1978年 | 39篇 |
1977年 | 24篇 |
1976年 | 26篇 |
1974年 | 31篇 |
1969年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Ketoconazole, an antifungal drug, completely inhibited the growth of Candida albicans 7N at concentrations of greater than or equal to 50 microgram/ml (94 microM). However, ketoconazole incompletely inhibited the growth of this opportunistic yeast at concentrations of 25 to 0.2 microgram/ml (47 to 0.4 microM). At these lower concentrations, 2,3,5-triphenyl tetrazolium chloride, an electron acceptor, was reduced by several strains of C. albicans. This effect resulted in red coloration of colonies. Concomitantly, this phenomenon was not antagonized in the presence of ergosterol. Furthermore, neither ketoconazole nor antimycin A inhibited the growth of C. albicans under anaerobic conditions, as revealed by a paper disk method. Ketoconazole at the concentrations stated above inhibited endogenous and exogenous respiration immediately after it was added to a system containing log phase C. albicans cells, as determined polarographically. At the same time, ketoconazole inhibited the activity of NADH oxidase at the mitochondrial level. In contrast, higher concentrations of ketoconazole (greater than 100 microM) were required to inhibit the activity of succinate oxidase from rat liver mitochondria. In addition, concentrations of ketoconazole greater than 100 microM were required to impair the uptake of labeled leucine and adenine and, subsequently, the incorporation of the former into protein and the latter into DNA and RNA in intact cells. On the other hand, ketoconazole at concentrations of 10, 1.0, and 0.4 microM had no effect on either membrane permeability or macromolecular synthesis. 相似文献
992.
Stereoselective Disposition of Sulbenicillin in Humans 总被引:1,自引:0,他引:1
Tomoo Itoh Naoko Watanabe Mariko Ishida Yasuyuki Tsuda Shinichi Koyano Tomoko Tsunoi Hideyo Shimada Hideo Yamada 《Antimicrobial agents and chemotherapy》1998,42(2):325-331
Stereoselective disposition of sulbenicillin (SBPC) epimers in healthy human volunteers was studied in order to clarify the differences in pharmacokinetic behavior between the epimers. Stereospecific high-performance liquid chromatography was used for the determination of SBPC epimers. Plasma protein binding was measured in vitro with an ultrafiltration method. The binding was stereoselective, with the unbound fraction (fu) of the R-epimer being approximately 1.3-fold greater than that of the S-epimer. SBPC was administered intravenously to human volunteers, and concentrations of SBPC in plasma and urinary excretion rates were measured. Renal clearance (CLR) for the unbound drug (approximately 400 ml/min) was greater than the glomerular filtration rate (GFR) (approximately 109 ml/min) for both epimers, suggesting that both epimers are secreted at the renal tubules. Renal tubular secretion appeared to be greater for the S-epimer. When probenecid was coadministered, the CLR values of both epimers were significantly reduced and were approximately equal to the GFR values. CLR was greater for the S-epimer (37.5 and 49.8 ml/min for R-SBPC and S-SBPC, respectively), which was simply due to the greater fu of the S-epimer in plasma. In contrast, total body clearance was greater for the R-epimer (67.8 and 56.3 ml/min for R-SBPC and S-SBPC, respectively) because of the stereoselective degradation of the R-epimer in plasma. It was revealed that stereoselective degradation in the body had significant influence on the disposition of SBPC epimers. 相似文献
993.
994.
Naohiro Ichino Yuji Horiguchi Hideo Imai Keisuke Osakabe Tohru Nishikawa Yukiko Sugita Hideko Utsugi Yoko Togo Tomoko Sawai Yoshikazu Mizoguchi 《Journal of Medical Ultrasonics》2006,33(1):29-35
Purpose The aim of this study was to evaluate the enhancement behavior of pancreatic ductal carcinoma by contrast-enhanced sonography
with agent detection imaging (ADI), and to clarify the origin of microbubble signals by comparisons with histological findings
of resected specimens.
Methods The subjects were 21 patients with resectable pancreatic carcinoma. The final histological diagnosis was tubular adenocarcinoma
in 20 cases, and anaplastic carcinoma in one case. Ultrasound examinations were performed using an Acuson Sequoia 512 series
system, and the contrast agent (Levovist) was injected intravenously in doses of 7 ml (300 mg/ml). The ADI signals (in the
tumor) were recorded continuously for 30 s after an injection of Levovist (vascular image) and then obtained intermittently
(30 s time-intervals) until the signal had diminished in pancreatic tissue (perfusion image).
Results Contrast enhancement of the tumor was observed in 71.4% of subjects on the vascular image and 76.3% of subjects on the perfusion
image. Enhancement patterns on the vascular image were classified into three types: VI-1 (linear enhancement), VI-2 (spotty
enhancement), and VI-3 (no enhancement). VI-1, VI-2, and VI-3 were seen in 9 (42.8%), 6 (28.6%), and 6 (28.6%) of the 21 cases,
respectively. Enhancement patterns on the perfusion image were classified into four types: PI-1 (diffuse uneven enhancement),
PI-2 (spotty enhancement), PI-3 (peripheral enhancement), and PI-4 (negative enhancement). The incidence of PI-1, PI-2, PI-3,
and PI-4 was 4.8%, 42.9%, 28.6%, and 23.8%, respectively. With respect to resectable cases, these enhancement patterns were
compared with histological findings, i.e., the distribution of blood vessels in the tumor, remaining pancreatic tissues in
the tumor, differentiation of types of adenocarcinoma, volume of stroma, and invasion types of carcinoma. The enhanced patterns
consequently corresponded to either the distribution of the blood vessels or the remaining pancreatic tissues in the tumor.
Conclusion This study indicated that pancreatic ductal carcinoma is frequently enhanced by microbubbles, and the signals seem to originate
from fine blood vessels and the remaining pancreatic tissues in the tumor. 相似文献
995.
KaiA-stimulated KaiC phosphorylation in circadian timing loops in cyanobacteria 总被引:20,自引:0,他引:20
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Iwasaki H Nishiwaki T Kitayama Y Nakajima M Kondo T 《Proceedings of the National Academy of Sciences of the United States of America》2002,99(24):15788-15793
Cyanobacterial clock proteins KaiA and KaiC are proposed as positive and negative regulators in the autoregulatory circadian kaiBC expression, respectively. Here, we show that activation of kaiBC expression by kaiA requires KaiC, suggesting a positive feedback control in the cyanobacterial clockwork. We found that robust circadian phosphorylation of KaiC. KaiA was essential for in vivo KaiC phosphorylation and activated in vitro KaiC autophosphorylation. These effects of KaiA were attenuated by the kaiA2 long period mutation. Both the long period phenotype and the abnormal KaiC phosphorylation in this mutant were suppressed by a previously undocumented kaiC mutation. We propose that KaiA-stimulated circadian KaiC phosphorylation is important for circadian timing. 相似文献
996.
A case of an epithelioid glioblastoma with the BRAF V600E mutation colocalized with BRAF intact low‐grade diffuse astrocytoma
下载免费PDF全文
![点击此处可从《Neuropathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jun‐Ichiro Kuroda Sumihito Nobusawa Hideo Nakamura Hideaki Yokoo Ryuta Ueda Keishi Makino Shigetoshi Yano Jun‐ichi Kuratsu 《Neuropathology》2016,36(2):181-186
Epithelioid glioblastomas are one of the rarest histological variants of glioblastomas, which are not formally recognized by the World Health Organization (WHO) classification. Epithelioid glioblastomas usually occur as primary lesions, but there have been several reports of secondary epithelioid glioblastomas or epithelioid glioblastomas with pre‐ or co‐existing lesions to date. The serine/threonine‐protein kinase B‐Raf (BRAF) V600E mutation has been found at a high frequency of 54% in epithelioid glioblastomas. We present a case of a 26‐year‐old female patient with an epithelioid glioblastoma with the BRAF V600E mutation in her right frontal lobe. In the present case, a low‐grade diffuse astrocytoma component had colocalized with the epithelioid glioblastoma. The component presented prominent calcification on neuroimages as well as by histology, and low‐grade diffuse astrocytoma was considered to be a precursor lesion of an epithelioid glioblastoma. However, the BRAF V600E mutation was detected only in epithelioid glioblastoma but not in low‐grade diffuse astrocytoma. To the best of our knowledge, this is the first report demonstrating a discrepancy in the BRAF V600E mutation states between epithelioid glioblastoma and colocalized low‐grade astrocytoma. 相似文献
997.
Akio Yamamoto Kenji Kihara Mariko Yagi Yoko Matsumoto Shuichi Tsuneishi Hideo Otaka 《Disability and rehabilitation. Assistive technology》2020,15(1):54-59
AbstractPurpose: Children with cerebral palsy may face difficulties using handheld pointing devices, due to involuntary muscle movements. This study aimed at describing the idea of the new wearable sensor switch and assessing its feasibility as an access solution in a case of mixed-type cerebral palsy.Methods: The study participant was a 17-year-old male with mixed-type cerebral palsy characterized by chorea-athetotic movements and bilateral spasticity with gross motor function classification system level V. He exhibited sudden and irregular involuntary upper limb movements when sitting. Because spastic finger movements limited his ability to use a handheld mouse, he used a trackball near his neck as a pointing device (previous input method). The wearable switch system using a stretchable strain sensor was introduced; the sensor was attached to a groove worn on the dorsal regions of the right hand crossing the proximal interphalangeal and metacarpophalangeal joints of the middle finger (new input method). The switch turned on when the subject flexed his middle finger.Results: The user successfully turned the switch on and typed almost the same numbers of characters per trial compared with the previous input method. The speed of his head movements during typing reduced (p?<?.01), and his sitting posture was nearly upright during computer operation (p?<?.01). No involuntary movement, requiring physical assistance, was observed when using the wearable switch.Conclusion: The new switch system can be a new option for people with difficulty using standard handheld input devices due to paralysis and involuntary muscle movements.
- Implications for rehabilitation
Cerebral palsy is a major cause of motor dysfunction and spasticity and dyskinesia in the fingers and upper limbs may prevent children with cerebral palsy from using handheld input devices.
Wearable devices may be useful for children with cerebral palsy who have limited access to handheld pointing devices.
We developed a new wearable switch to control devices using a flexible stretchable sensor.
The wearable switch contributed to the improvement of sitting posture and reduction of neck burden during the typing task at the speed equivalent to that using the previous method in a child with mixed type of cerebral palsy exhibiting choreoathetotic movements and bilateral spasticity.
998.
Selly Sayuri Suzuki Aguinaldo Silva Garcez Patricia Oblitas Reese Hideo Suzuki Martha Simões Ribeiro Won Moon 《Lasers in medical science》2018,33(4):811-821
The aim of this study was to compare the rate of tooth displacement, quantity of root resorption, and alveolar bone changes in five groups: corticopuncture (CP), low-level laser therapy (LLLT), CP combined with LLLT (CP?+?LLLT), control (C), and negative control (NC). A total of 60 half-maxilla from 30 male Wistar rats (10 weeks old) were divided randomly into five groups: three (CP, LLLT, and CP?+?LLLT) test groups with different stimulation for accelerated-tooth-movement (ATM), one control (C) group, and one negative control (NC) group with no tooth movement. Nickel-titanium coil springs with 50 g of force were tied from the upper left and right first molars to micro-implants placed behind the maxillary incisors. For the CP and CP?+?LLLT groups, two perforations in the palate and one mesially to the molars were performed. For the LLLT and CP?+?LLLT groups, GaAlAs diode laser was applied every other day for 14 days (810 nm, 100 mW, 15 s). The tooth displacements were measured directly from the rat’s mouth and indirectly from microcomputer (micro-CT) tomographic images. Bone responses at the tension and compression sites and root resorption were analyzed from micro-CT images. The resulting alveolar bone responses were evaluated by measuring bone mineral density (BMD), bone volume fraction (BV/TV), and trabecular thickness (TbTh). Root resorption crater volumes were measured on both compression and tension sides of mesial and distal buccal roots. The tooth displacement in the CP?+?LLLT group was the greatest when measured clinically, followed by the CP, LLLT, and control groups (C and NC), respectively (p?<0.05). The tooth movements measured from micro-CT images showed statistically higher displacement in the CP and CP?+?LLLT groups compared to the LLLT and control groups. The BMD, BV/TV, and TbTh values were lower at the compression side and higher at the tension side for all three test groups compared to the control group. The root resorption crater volume of the distal buccal root was higher in the control group, followed by CP, LLLT, and CP?+?LLLT, mostly at the compression site. Combining corticopuncture and low-level laser therapy (CP?+?LLLT) produced more tooth displacement and less root resorption at the compression side. The combined technique also promoted higher alveolar bone formation at the tension side. 相似文献
999.
Ishizawa K Obara Y Seki O Fujimaki S Kameoka J Ichinohasama R Kanemitsu K Sasaki T Kaku M Harigae H 《Clinica chimica acta; international journal of clinical chemistry》2004,344(1-2):79-82
BACKGROUND: It is sometimes difficult to detect the bone marrow infiltration of lymphoma cells, because lymphoma cells are not distinguishable from normal lymphocytes due to the similarity of their phenotype. METHODS: Bone marrow involvement of 17 samples of 15 patients with follicular lymphoma, whose lymphoma cells were confirmed to harbor the translocation of chromosome14q32, were examined by microscopic analysis of bone marrow smear and biopsy, flow cytometorical analysis (FCM), chromosomal analysis of G-banding and fluorescence in situ hybridization (FISH). FISH was performed using a probe, which detects the split of IGH gene on 14q32. RESULTS: The positivity of FISH was highest among these methods and FISH was able to detect the bone marrow involvement in one case who was defined as negative by bone marrow biopsy. CONCLUSIONS: FISH can be used for detection of bone marrow involvement of malignant lymphoma that carries chromosomal rearrangement involving 14q32. 相似文献
1000.
Hirano K Nomoto N Hirano M Momota F Hanada A Kanaide H 《The Journal of pharmacology and experimental therapeutics》2007,322(2):668-677
Proteinase-activated receptors 1 and 4 (PAR(1) and PAR(4)) are the major receptors mediating thrombin-induced NO production in endothelial cells. The intracellular signaling following their activation still remains to be elucidated. The present study provides the first evidence for the distinct Ca(2+) requirement for the NO production between PAR(1) and PAR(4). The activation of PAR(1) by the activating peptide (PAR(1)-AP) elevated cytosolic Ca(2+) concentrations ([Ca(2+)](i)) and activated NO production in porcine aortic and human umbilical vein endothelial cells, whereas it had little effect on bovine aortic endothelial cells. PAR(4) activation by PAR(4)-AP consistently induced NO production without an appreciable [Ca(2+)](i) elevation in three types of endothelial cells. The PAR(1)-mediated NO production was significantly inhibited by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), whereas the PAR(4)-mediated NO production was resistant. NO production following the PAR(1) and PAR(4) activation was significantly inhibited by pertussis toxin, but it was resistant to a Galpha(q/11) inhibitor, YM254890 [(1R)-1-[(3S,6S,9S,12S,18R,21S,22R)-21-acetamido-18-benzyl-3-[(1R)-1-methoxyethyl]-4,9,10,12,16,22-hexamethyl-15-methylene-2,5,8,11,14,17,20-heptaoxo-1,19-dioxa-4,7,10,13,16-pentaazacyclodocosan-6-yl]-2-methylpropyl rel-(2S,3R)-2-acetamido-3-hydroxy-4-methylpentanoate]. However, YM254890 abrogated the PAR(1)-mediated Ca(2+) signal. PAR(4)-mediated NO production was substantially inhibited by the inhibitors of phosphotidylinositol-3 kinase (PI3K) and Akt, as well as by the dominant negative mutant of Akt. The PAR(1)-mediated NO production was relatively resistant to inhibitors of PI3K. An immunoblot analysis revealed a transient increase in the phosphorylation of Akt and endothelial NO synthase following the PAR(4) stimulation. In conclusion, PAR(1) and PAR(4) engage distinct signal transduction mechanisms to activate NO production in vascular endothelial cells. PAR(4) preferably activates Galpha(i/o) and induced NO production in a manner mostly independent of Ca(2+) but dependent on the PI3K/Akt pathway, whereas PAR(1) activates both the Ca(2+)-dependent and -independent mechanisms. 相似文献