全文获取类型
收费全文 | 5502篇 |
免费 | 277篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 35篇 |
儿科学 | 111篇 |
妇产科学 | 80篇 |
基础医学 | 656篇 |
口腔科学 | 175篇 |
临床医学 | 387篇 |
内科学 | 1299篇 |
皮肤病学 | 135篇 |
神经病学 | 495篇 |
特种医学 | 229篇 |
外科学 | 698篇 |
综合类 | 30篇 |
预防医学 | 192篇 |
眼科学 | 109篇 |
药学 | 519篇 |
中国医学 | 39篇 |
肿瘤学 | 612篇 |
出版年
2023年 | 36篇 |
2022年 | 56篇 |
2021年 | 115篇 |
2020年 | 70篇 |
2019年 | 64篇 |
2018年 | 116篇 |
2017年 | 79篇 |
2016年 | 84篇 |
2015年 | 97篇 |
2014年 | 146篇 |
2013年 | 173篇 |
2012年 | 284篇 |
2011年 | 310篇 |
2010年 | 166篇 |
2009年 | 152篇 |
2008年 | 288篇 |
2007年 | 311篇 |
2006年 | 284篇 |
2005年 | 312篇 |
2004年 | 289篇 |
2003年 | 273篇 |
2002年 | 266篇 |
2001年 | 116篇 |
2000年 | 134篇 |
1999年 | 129篇 |
1998年 | 80篇 |
1997年 | 55篇 |
1996年 | 55篇 |
1995年 | 55篇 |
1994年 | 49篇 |
1993年 | 49篇 |
1992年 | 104篇 |
1991年 | 102篇 |
1990年 | 92篇 |
1989年 | 85篇 |
1988年 | 99篇 |
1987年 | 68篇 |
1986年 | 72篇 |
1985年 | 76篇 |
1984年 | 45篇 |
1983年 | 56篇 |
1982年 | 17篇 |
1981年 | 23篇 |
1979年 | 31篇 |
1977年 | 22篇 |
1975年 | 17篇 |
1974年 | 18篇 |
1973年 | 19篇 |
1972年 | 20篇 |
1967年 | 17篇 |
排序方式: 共有5801条查询结果,搜索用时 109 毫秒
41.
The cytoarchitectonic subnuclear organization of the parabrachial nucleus (PB) surrounding the brachium conjunctivum (BC) in the monkey was examined using the Nissl method and the anterograde axonal flow method. PB of the monkey could be divided into the following subnuclei: the dorsal area (DPBM) along the medial surface of the medial three-fourths of BC in the caudal half of medial PB (PBM), the ventral area (VPBM) along the medial surface of the lateral one-fourth of BC in the rostral two-thirds of PB, the ventrolateral part of lateral PB (PBL) lateral to BC throughout PB (EL), the ventral part of the rostral half of PBL ventral to EL (EXL), the medial part of middle PBL along the dorsal surface of BC (VL), the dorsal and lateral marginal part of PBL in the rostral two-thirds of PB (DL), the cell cluster in the dorsomedial part of the rostral half of PBL between VL and DL (CL), the dorsocentral part appearing at the level of root exit of the trochlear nerve between DL and CL and extending to the rostral end of PBL (IL), the area between DL and IL in the rostral one-seventh of PBL (SL), and K?lliker-Fuse nucleus (KF) ventral to EL and BC in the middle one-third of PB and lateral to the lateral pontine tegmentum. After the injection of biotinylated dextran amine into the upper cervical segments, labeled fibers terminated in each subdivision of PB with different densities; most heavily in IL, more heavily in DL and KF, moderately in EL and VPBM, and scarcely in the rest of PB. The present study demonstrated for the first time the subdivisions of PB in the monkey, which were essentially common to those of the rat based on the cytoarchictecture of PB and spinal fiber terminals in it. 相似文献
42.
Different immunosuppresive effects of anti-red blood cell sera and their fractions obtained from various animal species
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sheep red cells (RC) were coupled with HSA by means of an HSA—anti-SRBC IgG conjugate. The coupled RC were used to prepare rosettes with spleen cells of mice immunized to HSA in Freund's complete adjuvant. The rosettes were fractionated on discontinuous Ficoll gradients and the rosette-rich and rosette-poor fractions were tested for ability to transfer adoptively secondary responsiveness to HSA. Efficiency of transfer was measured in terms of haemagglutination titres. Memory of HSA was shown to be associated with rosette-forming cells, i.e. with cells carrying receptors for HSA. Several parameters of the adoptive transfer system employed were studied. The HSA-coupled RC proved to be very efficient in stimulating secondary responses to HSA. High titres of haemagglutinating antibodies (up to 1/80,000) were obtained with 10 × 106 spleen cells transferred and 2 × 106 spleen cells consistently gave titres of the order of 1/10,000. 相似文献
43.
We evaluated human physiological responses and the performance of manual tasks during exposure to severe cold (–25°C) at
night (0300–0500 hours) and in the afternoon (1500–1700 hours). Thirteen male students wearing standard cold protective clothing
occupied a severely cold room (–25°C) for 20 min, and were then transferred to a cool room (10°C) for 20 min. This pattern
of exposure was repeated three times, for a total time of exposure to extreme cold of 60 min. The experiments were started
either at 1500 hours or 0300 hours and measurements of rectal temperature, skin temperature, blood pressure, performance in
a counting task, hand tremor, and subjective responses were made in each condition. At the end of the experiment at night
the mean decrease in rectal temperature [0.68 (SEM 0.04)°C] was significantly greater than that at the end of the experiment
in the afternoon [0.55 (SEM 0.08)°C, P<0.01]. After the second cold exposure at night the mean increase in diastolic blood pressure [90 (SEM 2.0) mmHg] was significantly
greater than that at the end of the second cold exposure in the afternoon [82 (SEM 2.8) mmHg, P<0.01]. At the end of the second cold exposure at night, mean finger skin temperature [11.8 (SEM 0.8)°C] was significantly
higher than that at the comparable time in the afternoon [9.0 (SEM 0.7)°C, P<0.01]. Similarly for the toe, mean skin temperature at the start of the second cold exposure at night [25.6 (SEM 1.5)°C]
was significantly higher than in the afternoon [20.1 (SEM 0.8)°C, P<0.01]. The increased skin temperatures in the periphery resulted in increased heat loss. Since peripheral skin temperatures
were highest at night, the subjects noted diminished sensations of thermal cold and pain at that time. Manual dexterity at
the end of the first cold exposure at night [mean 83.7 (SEM 3.6) times·min–1] had decreased significantly more than at the end of the first cold exposure in the afternoon [mean 89.4 (SEM 3.5) times·min–1, P<0.01]. These findings of a lowered rectal temperature and diminished manual dexterity suggest that there is an increased
risk of both hypothermia and accidents for those who work at night.
Electronic Publication 相似文献
44.
K Nagai M Nagao M Nagao S Yanai K Minagawa Y Takahashi Y Takekoshi A Ishizaka Y Matsuzono O Kobayashi T Itagaki 《Journal of medical genetics》1998,35(4):342-344
We report a girl with oral, facial, and digital anomalies including multiple alveolar frenula, lobulated tongue with nodules, a posterior cleft palate, hypertelorism, a prominent forehead with a large anterior fontanelle, and postaxial polydactyly in both hands and the right foot, features compatible with the oral-facial-digital syndrome (OFDS). In addition, she had bilateral microphthalmia, optic disc coloboma, and retinal degeneration with partial detachment, thus establishing a diagnosis of OFDS type IX. Dandy-Walker malformation and retrobulbar cysts were observed on MRI. These additional malformations have not been reported in OFDS type IX. The frequent apnoeic spells which occurred immediately after birth were relieved after cystoperitoneal shunt implantation for hydrocephalus. Considering our case and previous reports of OFDS type IX, including two male sibs, a boy born to consanguineous parents, and three females, inheritance is probably autosomal recessive. 相似文献
45.
Hepatitis C virus down-regulates insulin receptor substrates 1 and 2 through up-regulation of suppressor of cytokine signaling 3 总被引:15,自引:0,他引:15
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Kawaguchi T Yoshida T Harada M Hisamoto T Nagao Y Ide T Taniguchi E Kumemura H Hanada S Maeyama M Baba S Koga H Kumashiro R Ueno T Ogata H Yoshimura A Sata M 《The American journal of pathology》2004,165(5):1499-1508
The pathogenesis of hepatitis C virus (HCV)-associated insulin resistance remains unclear. Therefore, we investigated mechanisms for HCV-associated insulin resistance. Homeostasis model assessment for insulin resistance was increased in patients with HCV infection. An increase in fasting insulin levels was associated with the presence of serum HCV core, the severity of hepatic fibrosis and a decrease in expression of insulin receptor substrate (IRS) 1 and IRS2, central molecules of the insulin-signaling cascade, in patients with HCV infection. Down-regulation of IRS1 and IRS2 was also seen in HCV core-transgenic mice livers and HCV core-transfected human hepatoma cells. Carbobenzoxy-l-leucyl-l-leucyl-l-leucinal, a potent proteosomal proteolysis inhibitor, blocked down-regulation of IRS1 and IRS2 in HCV core-transfected hepatoma cells. In human hepatoma cells, HCV core up-regulated suppressor of cytokine signaling (SOCS) 3 and caused ubiquitination of IRS1 and IRS2. HCV core-induced down-regulation of IRS1 and IRS2 was not seen in SOCS3(-/-) mouse embryonic fibroblast cells. Furthermore, HCV core suppressed insulin-induced phosphorylation of p85 subunit of phosphatidylinositol 3-kinase and Akt, activation of 6-phosphofructo-2-kinase, and glucose uptake. In conclusion, HCV infection changes a subset of hepatic molecules regulating glucose metabolism. A possible mechanism is that HCV core-induced SOCS3 promotes proteosomal degradation of IRS1 and IRS2 through ubiquitination. 相似文献
46.
Neurotoxicity of Clostridium perfringens Epsilon-Toxin for the Rat Hippocampus via the Glutamatergic System
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Osamu Miyamoto Junzaburo Minami Tetsuhiko Toyoshima Takehiro Nakamura Tetsuya Masada Seigo Nagao Tetsuro Negi Toshifumi Itano Akinobu Okabe 《Infection and immunity》1998,66(6):2501-2508
The neurotoxicity of epsilon-toxin, one of the major lethal toxins produced by Clostridium perfringens type B, was studied by histological examination of the rat brain. When the toxin was injected intravenously at a lethal dose (100 ng/kg), neuronal damage was observed in many areas of the brain. Injection of the toxin at a sublethal dose (50 ng/kg) caused neuronal damage predominantly in the hippocampus: pyramidal cells in the hippocampus showed marked shrinkage and karyopyknosis, or so-called dark cells. The dark cells lost the immunoreactivity to microtubule-associated protein-2, a postsynaptic somal and dendric marker, while acetylcholinesterase-positive fibers were not affected. Timm’s zinc staining revealed that zinc ions were depleted in the mossy layers of the CA3 subfield containing glutamate as a synaptic transmitter. The cerebral blood flow in the hippocampus was not altered significantly before or after administration of the toxin, as measured by laser-Doppler flowmetry, excluding the possibility that the observed histological change was due to a secondary effect of ischemia in the hippocampus. Prior injection of either a glutamate release inhibitor or a glutamate receptor antagonist protected the hippocampus from the neuronal damage caused by epsilon-toxin. These results suggest that epsilon-toxin acts on the glutamatergic system and evokes excessive release of glutamate, leading to neuronal damage. 相似文献
47.
Nascent peptide-mediated translation elongation arrest coupled with mRNA degradation in the CGS1 gene of Arabidopsis
下载免费PDF全文
![点击此处可从《Genes & development》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Onouchi H Nagami Y Haraguchi Y Nakamoto M Nishimura Y Sakurai R Nagao N Kawasaki D Kadokura Y Naito S 《Genes & development》2005,19(15):1799-1810
Expression of the Arabidopsis CGS1 gene that codes for cystathionine gamma-synthase is feedback regulated at the step of mRNA stability in response to S-adenosyl-L-methionine (AdoMet). A short stretch of amino acid sequence, called the MTO1 region, encoded by the first exon of CGS1 itself is involved in this regulation. Here, we demonstrate, using a cell-free system, that AdoMet induces temporal translation elongation arrest at the Ser-94 codon located immediately downstream of the MTO1 region, by analyzing a translation intermediate and performing primer extension inhibition (toeprint) analysis. This translation arrest precedes the formation of a degradation intermediate of CGS1 mRNA, which has its 5' end points near the 5' edge of the stalled ribosome. The position of ribosome stalling also suggests that the MTO1 region in nascent peptide resides in the ribosomal exit tunnel when translation elongation is temporarily arrested. In addition to the MTO1 region amino acid sequence, downstream Trp-93 is also important for the AdoMet-induced translation arrest. This is the first example of nascent peptide-mediated translation elongation arrest coupled with mRNA degradation in eukaryotes. Furthermore, our data suggest that the ribosome stalls at the step of translocation rather than at the step of peptidyl transfer. 相似文献
48.
Toshitaka Nagao Thomas A Gaffey Hiromi Serizawa Isamu Sugano Yasuo Ishida Kazuto Yamazaki Ryoji Tokashiki Tomoyuki Yoshida Hiroshi Minato Paul A Kay Jean E Lewis 《Modern pathology》2003,16(12):1265-1272
Dedifferentiated adenoid cystic carcinomas are a recently defined, rare variant of adenoid cystic carcinomas characterized histologically by two components: conventional low-grade adenoid cystic carcinoma and high-grade "dedifferentiated" carcinoma. We examined six cases and analyzed their clinicopathologic profiles, including immunohistochemical features and p53 gene alterations. The 6 patients (3 men and 3 women) had a mean age of 46.8 years (range, 34-70 y). The mean size of the tumors was 3.5 cm (range, 1.7-6 cm). The submandibular gland, maxillary sinus, and nasal cavity were involved in 2 cases each. Postoperatively, 5 patients had local recurrence and 5 developed metastatic disease. Five patients died of disease at a mean of 33.7 months after diagnosis (range, 6-69 mo), and one other was alive with disease at 60 months. Histologically, the conventional low-grade adenoid cystic carcinoma component of the tumors consisted of a mixture of cribriform and tubular patterns with scant solid areas. The high-grade dedifferentiated carcinoma component was either a poorly differentiated adenocarcinoma (4 cases) or undifferentiated carcinoma (2 cases). Three tumors were studied immunohistochemically. Myoepithelial markers were expressed in low-grade adenoid cystic carcinoma but not in the dedifferentiated component. In 2 cases, diffusely positive p53 immunoreactivity together with HER-2/neu overexpression was restricted to the dedifferentiated component. Loss of pRb expression was demonstrated only in the dedifferentiated component of the 1 other case. The Ki-67-labeling index was higher in the dedifferentiated component than in the low-grade adenoid cystic carcinoma component. Furthermore, molecular analysis of 2 cases demonstrated the loss of heterozygosity at p53 microsatellite loci, accompanied by p53 gene point mutation, only in the dedifferentiated carcinoma component of 1 case, which was positive for p53 immunostaining. These results indicate that dedifferentiated adenoid cystic carcinoma is a highly aggressive tumor. Because of frequent recurrence and metastasis, the clinical course is short, similar to that of adenoid cystic carcinomas with a predominant solid growth pattern. Limited evidence suggests that p53 abnormalities in combination with HER-2/neu overexpression or loss of pRb expression may have a role in dedifferentiation of adenoid cystic carcinoma. 相似文献
49.
Invasion of rat fibroblastic cells Rat-1 through Matrigel was shown to be promoted by transfection with tax gene of human T-cell leukemia virus type 1. We found that an oxidation-resistant type of vitamin C (Asc), Asc-2-O-phosphate (Asc2P), inhibited the invasion of the tax-transfected Rat-1 cells (W4 cells). Intracellular Asc (Ascin), after enzymatic dephosphorylation of administered Asc2P, was more abundant in W4 cells than in Rat-1 cells, and the ratio of dehydroascorbic acid versus Asc was increased in W4 cells but scarcely in Rat-1 cells, according to the enhanced level of intracellular reactive oxygen species (ROSin) in W4 cells. Asc2P notably repressed the increases in both ROSin and secretion of matrix metalloproteases (MMPs), but did not affect Tax protein expression in tax-transfectants. NF-kappa B activation, as evidenced by its translocation to the nucleus in W4 cells, was also repressed by Asc2P. Thus, the tax-promoted invasion together with the enhanced production of MMPs occurred with NF-kappa B activation and the increase in ROSin, both of which were effectively reduced by Asc2P. These findings indicate the therapeutic efficacy of Ascin-enriching agents for the prevention against tumor invasion in which ROSin plays a major role. 相似文献
50.
X-linked mixed deafness (DFN3): cloning and characterization of the critical region allows the identification of novel microdeletions 总被引:5,自引:0,他引:5
Huber Irene; Bitner-Gllndzicz Maria; de Kok Yvette J.M.; van der Maarel Silvere M.; Ishikawa-Brush Yumiko; Monaco Anthony P.; Robinson David; Malcolm Susan; Pembrey Marcus E.; Brunner Han G.; Cremers Frans P.M.; Ropers Hans-Hilger 《Human molecular genetics》1994,3(7):1151-1154
We have found that the microsatellite marker AFM207zg5 (DXS995)maps to all previously described deletions which are associatedwith X-linked mixed deafness (DFN3) with or without choroideremiaand mental retardation. Employing this marker and pHU16 (DXS26)we have identified two partially overlapping yeast artificialchromosome clones which were used to construct a complete 850kb cosmid contig. Cosmids from this contig have been testedby Southern blot analysis on DNA from 16 unrelated males withX-linked deafness. Two novel microdeletions were detected inpatients which exhibit the characteristic DFN3 phenotype. Bothdeletions are completely contained within one of the known DFN3-deletions,but one of them does not overlap with two previously describeddeletions in patients with contiguous gene syndromes consistingof DFN3, chorolderemia, and mental retardation. Assuming thatonly a single gene is involved, this suggests that the DFN3gene spans a chromosomal region of at least 400 kb. 相似文献