全文获取类型
收费全文 | 10652篇 |
免费 | 634篇 |
国内免费 | 60篇 |
专业分类
耳鼻咽喉 | 156篇 |
儿科学 | 233篇 |
妇产科学 | 269篇 |
基础医学 | 1708篇 |
口腔科学 | 220篇 |
临床医学 | 666篇 |
内科学 | 2377篇 |
皮肤病学 | 385篇 |
神经病学 | 676篇 |
特种医学 | 418篇 |
外科学 | 1561篇 |
综合类 | 30篇 |
一般理论 | 3篇 |
预防医学 | 447篇 |
眼科学 | 173篇 |
药学 | 779篇 |
中国医学 | 16篇 |
肿瘤学 | 1229篇 |
出版年
2023年 | 70篇 |
2022年 | 83篇 |
2021年 | 225篇 |
2020年 | 127篇 |
2019年 | 178篇 |
2018年 | 189篇 |
2017年 | 176篇 |
2016年 | 233篇 |
2015年 | 225篇 |
2014年 | 282篇 |
2013年 | 349篇 |
2012年 | 555篇 |
2011年 | 597篇 |
2010年 | 312篇 |
2009年 | 320篇 |
2008年 | 531篇 |
2007年 | 568篇 |
2006年 | 572篇 |
2005年 | 494篇 |
2004年 | 509篇 |
2003年 | 491篇 |
2002年 | 455篇 |
2001年 | 356篇 |
2000年 | 362篇 |
1999年 | 326篇 |
1998年 | 131篇 |
1997年 | 107篇 |
1996年 | 73篇 |
1995年 | 68篇 |
1994年 | 48篇 |
1993年 | 51篇 |
1992年 | 201篇 |
1991年 | 169篇 |
1990年 | 188篇 |
1989年 | 202篇 |
1988年 | 206篇 |
1987年 | 166篇 |
1986年 | 150篇 |
1985年 | 135篇 |
1984年 | 107篇 |
1983年 | 83篇 |
1979年 | 56篇 |
1978年 | 38篇 |
1977年 | 44篇 |
1975年 | 36篇 |
1974年 | 43篇 |
1973年 | 51篇 |
1972年 | 43篇 |
1970年 | 47篇 |
1968年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 890 毫秒
21.
Localization of ferritin using a pre-embedding diffusion technique and an indirect localization sequence has been made in 34 cases of human liver under normal and several pathological conditions. With light microscopic observation, positive immuno-staining for ferritin was demonstrated as diffuse deposits in the hepatocytes and Kupffer cells. Intensity of the positive immuno-staining for ferritin in these cells appeared to roughly coincide with serum ferritin levels of each patient, but showed no disease specificity, although hepatoma cells contained weak deposits or were negative from immuno-staining for ferritin. With electron microscopic studies, intracellular antigen was well preserved in the hepatocytes and Kupffer cells in most cases with the positive immuno-staining for ferritin being observed in cytosol and a few cisternae of rough endoplasmic reticulum. Content of the positive immuno-staining for ferritin differed considerably from one case to another and one cell to another even in the same case. There was no immuno-staining for ferritin in hemosiderin pigment, lysosome, most of rough endoplasmic reticulum, Golgi complexes, and nucleus in both cells. 相似文献
22.
Yasuomi Ouchi Teiji Nakayama Toshihiko Kanno Etsuji Yoshikawa Tomomi Shinke Tatsuo Torizuka 《Journal of cerebral blood flow and metabolism》2007,27(4):803-810
Differentiation of impaired gait seen in idiopathic normal pressure hydrocephalus (iNPH) from parkinsonian gait is sometimes a great challenge and important for future medication in the clinical setting. To investigate dopaminergic contribution to its pathophysiology, two aspects of the trans-synaptic dopamine functions in the striatal region in eight iNPH patients na?ve to dopaminergic drugs were examined using positron emission tomography with a presynaptic marker [11C]CFT ([11C]2-beta-carbomethoxy-3beta-(4-fluorophenyl) tropane) that binds to dopamine transporter and a postsynaptic marker [11C]raclopride that binds to D2 receptor. Quantitative values of binding potentials (BPs) for [11C]CFT and [11C]raclopride were compared between patients and eight age-matched healthy subjects. The BPs and magnetic resonance imaging-based morphometric measures in iNPH were used for correlation analyses between the magnitude of binding of these in vivo markers and clinical severity of the patients. Analysis of variance showed significant reduction in [11C]raclopride binding in the putamen and nucleus accumbens (P<0.05, corrected for multiple comparison) and unchanged striatal [11C]CFT binding in iNPH. The dorsal putamen [11C]raclopride binding correlated negatively with gait severity (r=0.720, P<0.05), and the nucleus accumbens [11C]raclopride binding correlated positively with emotional recognition score (r=0.727, P<0.05) in the disease group. No significant relationship was observed between BPs and morphometric measures. The current result of the postsynaptic D2 receptor reduction along with preserved presynaptic activity in the nigrostriatal dopaminergic system reflects a pathophysiology of iNPH. Postsynaptic D2 receptor hypoactivity in the dorsal putamen may predict the severity of gait impairment in iNPH. 相似文献
23.
Structural determination of geometrical isomers of microcystins LR and RR from cyanobacteria by two-dimensional NMR spectroscopic techniques 总被引:6,自引:0,他引:6
K Harada K Ogawa K Matsuura H Murata M Suzuki M F Watanabe Y Itezono N Nakayama 《Chemical research in toxicology》1990,3(5):473-481
A nondestructive method using a combination of three 2D NMR techniques, DQF-COSY (double quantum filter correlation spectroscopy), HMQC (1H-detected multiple quantum coherence), and HMBC (heteronuclear multiple bond correlation), were developed for structural determination of microcystins, toxic heptapeptides produced by cyanobacteria. With this procedure we were able to assign all carbons and protons of microcystins LR (1) and RR (2), thus determining the constituent amino acid sequences. The procedure was also applied to the microcystin-associated nontoxic minor components, which have molecular weights and amino acid compositions similar to those of 1 and 2 and toxicities different from those of 1 and 2. From detailed analysis of these spectra we rapidly deduced that the minor components are geometrical isomers with respect to C-7 of the diene in Adda of the parent toxins. The structures were finally confirmed to be 3 and 4 by ROESY (rotating frame nuclear Overhauser and exchange spectroscopy) technique. 相似文献
24.
Shigeki Ohgitani Akimitsu Miyauchi Yasuyuki Takagi Yoshio Fujii Takuo Fujita Misa Nakamura Zhi-qiang Zhang Liang Shan Mitsuyo Sasaki Ryuichi Tsukino Toyoharu Yokoi Kennichi Kakudo Tomitaka Nakayama Junya Toguchida Hiroshi Kanoe Shinichi Aizawa Masao S. Sasaki Takashi Nakamura M. Suda K. Tanaka Y. Ogawa N. Tamura A. Yasoda H. Itoh M. Uehira N. Nishimoto T. Takigawa K. Shiota K. Nakao 《Journal of bone and mineral metabolism》1997,15(3):165-171
25.
Japan Pancreatoduodenectomy Study Group Ryo Hosotani Masafumi Kogire Tadahiro Takada Hiroyuki Kato Takahiko Funabiki Masumasa Horisawa Takeshi Morimoto Takukazu Nagakawa Toshimichi Nakayama Itsuo Miyazaki Masayuki Imamura 《Journal of Hepato-Biliary-Pancreatic Surgery》1997,4(3):295-303
Endocrine tumor of the pancreas is potentially malignant. A multicenter analysis of these tumors was conducted to clarity
the present status of their surgical management and the subsequent long-term surgical results. The Japan pancreatoduodenectomy
(JPD) study group carried out the study; 368 patients were enrolled and variables related to tumor characteristics, surgery,
and survival were retrospectively analyzed. There were 222 patients with functioning tumor and 143 patients with nonfunctioning
tumor. Malignant tumor was found in 140 of 368 (38%) of the patients, and 63/140 (45%) of these patients had metastatic lesion;
the most common site of the metastasis was liver 34/136 (25%), followed by regional lymph nodes 26/136 (19%). Pancreatic resection
was performed in 91% of patients with nonfunctional tumor and in 83% of those with malignant tumor, and 73% of the pancreatic
resections were done with lymph node dissection. The overall 5-year actuarial survival rate was 76% in patients with malignant
tumor. The actuarial 5-year survival rate was 93% in the patients without metastasis and 83% in patients who received curative
resection. Multivariate analysis showed that the presence or absence of synchronous metastasis was the sole significant prognostic
factor. The results suggest that: (i) malignant endocrine tumor of the pancreas is a curable malignancy when pancreatic resection
with lymph node dissection is adopted and (ii) that synchronous metastasis is the dominant prognostic factor.
This study was carried out as a group project. The authors' institutions are as follows 相似文献
26.
I. Gorai Y. Taguchi O. Chaki M. Nakayama H. Minaguchi 《Calcified tissue international》1997,60(4):317-322
Urinary excretion of cross-linked N-telopeptide of type I collagen (NTx) has been reported to be a specific marker of bone
resorption [18]. We assessed a new immunoassay for NTx as an indicator of changes in bone resorption caused by spontaneous
menopause and compared cross-sectionally the levels of urinary NTx, hydroxylysylpyridinoline (HP), lysylpyridinoline (LP),
hydroxyproline (OH-Pr), other serum biochemical indices, and lumbar spine and proximal femur bone mineral density (BMD). Eighty-one
Japanese women aged 22–77 participated in this study; 36 were premenopausal and 45 were postmenopausal. Urinary HP, LP, and
NTx stayed at low levels in the premenopausal period and rose 21%, 30%, and 67% in the postmenopausal period, respectively.
The rise in LP and NTx was statistically significant (P < 0.01), suggesting that NTx is mostly released from bone matrix when bone resorption is accelerated. When premenopausal
women were divided into two age groups and postmenopausal women were divided into two groups according to years since menopause
(YSM) there were significant differences in LP and NTx between women <4 YSM and women aged <40 and those women aged 41+ (P < 0.01 and P < 0.05, respectively). A significant 110% increase in urinary NTx and a 48% increase in urinary LP were observed in postmenopausal
women compared with age-matched premenopausal women aged 45–55. All biochemical markers other than serum PTH correlated significantly
with each other (r = 0.243–0.858, P < 0.05–0.0001). Urinary NTx inversely correlated with lumbar spine BMD. When postmenopausal women were divided into three
groups, the correlation between bone resorption and formation markers in women 0-1 YSM was greater than in women 2–10 YSM
and in women 11 + YSM, indicating that resorption and formation are coupled at the early postmenopausal period. We conclude
that urinary NTx is responsive to changes in bone metabolism caused by estrogen deficiency and may be a more sensitive and
specific marker than HP, LP, or OH-Pr in the early postmenopausal years.
Received: 15 February 1995 / Accepted: 18 October 1996 相似文献
27.
Ruthenium red (3-5 microM) antagonism of the inhibitory effect of capsaicin (1 microM) on the contractile response to mesenteric nerve stimulation in the presence of hexamethonium (50 microM) and guanethidine (2 microM) was reversed significantly by sialic acid (2 mM) or neuraminidase (0.1 U/ml). These results suggested that ruthenium red at low concentrations inhibits the capsaicin-induced desensitization of activated Ca2+ influx into sensory nerves at least in part by binding to sialic acid residues. 相似文献
28.
29.
We investigated populations of the infiltrating cells in Bowen's disease (BD) and squamous cell carcinoma (SCC), both of which arose in the same patient, using the Avidin-Biotin-peroxidase complex method with eight monoclonal antibodies. T lymphocytes were most predominant among infiltrating cells; NK cells, B cells, and monocytes were rarely seen in either BD or SCC. Analysis of subsets of the infiltrating T lymphocytes revealed that the number of suppressor/cytotoxic (s/c) T cells was twice that of helper/inducer (h/i) T cells in BD, while the number of s/c T cells was lower than that of h/i T cells in SCC. The immunohistochemical results in the present case differed from those of predominant infiltration of h/i T cells and of s/c T cells in three other reports of BD and SCC. These results suggest that the population of the cellular infiltrates may be modulated by the nature of tumors and by the immuno-competent state of the hosts. 相似文献
30.
K Ishino T Murakami H Nakayama M Yamada T Morimoto K Hisamochi T Tanaka Y Senoo S Teramoto 《Acta medica Okayama》1991,45(4):223-231
A biventricular bypass type total artificial heart (BVB-TAH) utilizing two pusher-plate pumps was developed and implanted in a sheep for 48 days with excellent results. A Hall effect sensor was utilized to operate each pump independently with a full stroke at variable rates (VR). With this system, the animal's hemodynamics was kept physiologically, and all metabolic parameters except hemoglobin and hematocrit returned to normal three weeks after implantation. However, signs of infection appeared on the forty-second day, and consequently the animal fell into a state of shock. Even at that time the BVB-TAH maintained circulation by increasing pumping rate automatically. On the forty-eighth day, the animal could not stand and suffered from anuria; the experiment was then terminated after 1,140 h pumping. At autopsy, there was an enlarged heart with an atrophic change, 1,900 ml of pleural effusion, and 3,100ml of ascites fluid. Blood culture taken on the forty-seventh day yielded Acinetobacter calcoaceticus. The BVB-TAH operated in an independent VR mode maintained entire circulation, and has a capability of substituting the native heart function in any situation. 相似文献