首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   129294篇
  免费   7003篇
  国内免费   178篇
耳鼻咽喉   1893篇
儿科学   5507篇
妇产科学   4259篇
基础医学   17948篇
口腔科学   3176篇
临床医学   9749篇
内科学   24766篇
皮肤病学   3585篇
神经病学   9933篇
特种医学   5659篇
外国民族医学   48篇
外科学   20781篇
综合类   1723篇
一般理论   35篇
预防医学   7093篇
眼科学   3554篇
药学   8943篇
中国医学   343篇
肿瘤学   7480篇
  2018年   1135篇
  2017年   928篇
  2016年   1320篇
  2015年   1460篇
  2014年   1919篇
  2013年   2802篇
  2012年   3694篇
  2011年   3740篇
  2010年   2308篇
  2009年   2278篇
  2008年   3818篇
  2007年   4047篇
  2006年   4191篇
  2005年   4281篇
  2004年   4208篇
  2003年   4090篇
  2002年   4008篇
  2001年   7495篇
  2000年   7479篇
  1999年   6321篇
  1998年   1810篇
  1997年   1706篇
  1996年   1481篇
  1995年   1327篇
  1994年   1201篇
  1993年   1231篇
  1992年   4112篇
  1991年   3869篇
  1990年   3843篇
  1989年   3595篇
  1988年   3245篇
  1987年   3114篇
  1986年   3058篇
  1985年   2845篇
  1984年   2128篇
  1983年   1762篇
  1982年   1023篇
  1981年   1006篇
  1980年   861篇
  1979年   1966篇
  1978年   1451篇
  1977年   1205篇
  1976年   1005篇
  1975年   1260篇
  1974年   1313篇
  1973年   1306篇
  1972年   1110篇
  1971年   1059篇
  1970年   940篇
  1969年   839篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
73.
74.
A mutant form of ammodytoxin A, a neurotoxic phospholipase A2 from the venom of the long nosed viper Vipera ammodytes ammodytes, was prepared by site-directed mutagenesis, conjugated to a nanogold particle and inoculated into the antero-lateral aspect of one hind limb of female mice. Eight hours later the mice were killed, the soleus muscles of both ipsi- and contra-lateral hind limbs were removed, exposed to a silver enhancing medium and then prepared for transmission electron microscopy. Silver-enhanced particles were subsequently found concentrated in the peri-synaptic area, particularly within the synaptic gutter and the deep synaptic folds, and in many cases had been taken up into the cytoplasm of the terminal boutons of the motor axon. The results suggest that the presynaptic neurotoxicity of snake venom phospholipases A2 involves several components of the neuromuscular apparatus, including intracellular organelles of the motor nerve terminal.  相似文献   
75.
A microfluorometric method was used to determine the nuclear DNA content in the nasopharyngeal carcinomas (NPC) of 25 patients treated before 1983. Eleven patients are still alive with no evidence of disease (NED), while the rest died of their disease (DOD). All of the patients received a cycle of radiotherapy, while some also received chemotherapy or neck dissections. The neoplastic cells studied were taken from the original biopsy blocks, deparaffinized, isolated by enzymatic treatment and mechanical fragmentation, and then Feulgen-stained. The cytofluorometric measurement was carried out by a microphotometer equipped for fluorescence excitation and connected to a computer. This method allowed us to construct a histogram of the DNA content in the neoplastic cells. Different neoplastic classes were identified and represent the heteroclonality of the tumor, which can be expressed by the heteroclonality index (HCT). From the collected data it appears that the NED patients all had a low HTC (less than 1) and only 7 of the DOD patients had low HTCs (less than 1). Six of the DOD patients with a low HTC were in advanced stages of their tumor at the time of diagnosis, while the remaining patient did not complete his treatment. Our results show that the DNA analysis of the NPC cell population may offer a useful tool in predicting the biological behavior of this tumor and also improving its treatment.  相似文献   
76.
K Rehse  U Lükens  G Claus 《Archiv der Pharmazie》1987,320(12):1233-1238
Platelet Aggregation Inhibiting and Anticoagulant Effects of Oligoamines, VII: Benzene-1,3,5-trialkanamines Seventeen title compounds were synthesized. Platelet aggregation induced by collagen in vitro is inhibited by 9 of them at IC50 = 2–4 μmol/L. Seven compounds depress the formation of fibrin to ≦ 25 % of normal in concentrations below 50 μmol/L. Compound 15 [4-(2-thienylbutyl)benzene-1,3,5-trimethanamine is the first oligoamine which shows anticoagulant and antiplatelet effects at the same concentration (25 μmol/L).  相似文献   
77.
The livers of 26 adult males with acquired immune deficiency syndrome (AIDS) were reviewed. The occurrence of portal tracts with diminished lymphocytes, probably reflecting generalized exhaustion of the lymphoid system, was a characteristic morphologic change, and was found in all cases. Kupffer cell hyperplasia was also a frequent finding and probably reflected generalized infection(s). Punched-out clusters of foamy histiocytes filled with acid-fast bacilli, typical for infection with Mycobacterium avium intracellulare (MAC), were found in three patients. In addition, MAC was cultured from two livers without the foamy histiocytic changes. Chronic viral hepatitis (three cases) and deposition of polarizable materials (one case) in the liver might be related to unusual habits of patients with AIDS. In conclusion, livers from patients with AIDS disclosed several kinds of lesions reflecting underlying or associated conditions in AIDS, but these did not contribute to the cause of death in our patients.  相似文献   
78.
Phenytoin-induced gingival overgrowth is a recognized side effect in many cerebral palsy patients using diphenyl hydantoin for the control of seizures. Severe gingival overgrowth in these patients can affect normal masticatory function, lead to poor occlusal development, and compromise esthetics. This report addresses the complex nature of treating phenytoin-induced gingival overgrowth in a mentally retarded 20-year-old female patient. For this patient, full-mouth gingivectomy procedure was performed under general anesthesia in a single session. Post operative follow-up was uneventful. This article discusses major indications, contraindications, and protocols to be followed for periodontal surgical procedures done under general anesthesia.  相似文献   
79.
80.
The study presented here was conducted to evaluate the performance of the newly available RIDASCREEN Set (R-Biopharm AG, Darmstadt, Germany) for the detection of immunoglobulin G antibodies against Entamoeba histolytica. The sensitivity and specificity of this new enzyme-linked immunosorbent assay were evaluated using a panel of sera from 239 individuals. The assay was positive for 43 of 44 patients with invasive amebiasis, including all 18 patients with amebic liver abscess, while it was negative for 190 of 195 adult controls who were either healthy individuals or patients with other parasitic diseases. The kit was found to be highly specific (97.4%) and sensitive (97.7%) for detecting antibodies against E. histolytica in humans. Although antibody titers in patients with amebic liver abscess tend to be higher on average than in patients with invasive amebiasis, it is not possible to distinguish the two forms solely based on the results of this commercial test.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号