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   10376篇
  免费   739篇
  国内免费   37篇
耳鼻咽喉   82篇
儿科学   296篇
妇产科学   297篇
基础医学   1413篇
口腔科学   235篇
临床医学   1283篇
内科学   2052篇
皮肤病学   259篇
神经病学   1081篇
特种医学   194篇
外科学   903篇
综合类   66篇
一般理论   16篇
预防医学   1310篇
眼科学   186篇
药学   683篇
中国医学   32篇
肿瘤学   764篇
  2024年   16篇
  2023年   132篇
  2022年   227篇
  2021年   463篇
  2020年   263篇
  2019年   359篇
  2018年   376篇
  2017年   275篇
  2016年   314篇
  2015年   316篇
  2014年   393篇
  2013年   583篇
  2012年   838篇
  2011年   842篇
  2010年   480篇
  2009年   374篇
  2008年   644篇
  2007年   635篇
  2006年   575篇
  2005年   547篇
  2004年   465篇
  2003年   447篇
  2002年   393篇
  2001年   45篇
  2000年   35篇
  1999年   42篇
  1998年   69篇
  1997年   68篇
  1996年   61篇
  1995年   51篇
  1994年   40篇
  1993年   45篇
  1992年   33篇
  1991年   32篇
  1990年   26篇
  1989年   25篇
  1988年   27篇
  1987年   28篇
  1986年   27篇
  1985年   27篇
  1984年   33篇
  1983年   39篇
  1982年   35篇
  1981年   35篇
  1980年   41篇
  1979年   13篇
  1978年   17篇
  1977年   18篇
  1975年   14篇
  1973年   15篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Vesicular stomatitis virus (VSV), when reproduced in human tumor cell lines, assembled a specific subset of cell-derived proteins. These were detected by [35S]methionine labeling of cells prior to infection and subsequent immunoprecipitation of VSV grown in these cells, as well as by direct immunoprecipitation of labeled cell extracts with antiserum directed against the VSV-assembled proteins. Their molecular weight (Mr) ranged between 15K and 180K; the larger proteins were glycosylated. Two of the major protein species (gp88 and gp130) were common to all four cell lines used (HeLa—cervical carcinoma, T47D—breast carcinoma, and HMB2 and SK1477—two melanoma cell lines). Proteins of other molecular weights were detected only in one or two of the cell lines. The melanoma cell lines (even in the absence of VSV) shed large particulate material which had contained the same spectrum of proteins that were assembled by VSV. The major protein component had an Mr of 30K. Some of the VSV-assembled proteins might possibly serve as specific tumor markers. It is also conceivable that the proteins assembled by VSV as well as the large particulate material might be products of defective endogenous human retroviruses.  相似文献   
42.
The critical distinction of bronchioloalveolar carcinoma (BAC), well-differentiated adenocarcinoma (WDAC) of lung, adenomatous hyperplasia (AH) and atypical adenomatous hyperplasia (AAH), is based on morphological criteria alone, and is therefore potentially subjective. We examined expression of two markers, X-linked inhibitor of apoptosis protein (XIAP), the most potent of the inhibitor of apoptosis protein (IAP) family, and p63, a marker of bronchial reserve cells (BRC) and squamous cells, in these entities. H&E slides of 37 tissue blocks from 27 patients were reviewed and classified as AH (n=7), AAH (n=8), BAC (n=9) and WDAC (n=13). Immunostaining was performed on 4 mum sections with monoclonal anti-XIAP and monoclonal anti-p63. Granular or heterogeneous cytoplasmic staining for XIAP and nuclear staining for p63 were considered positive. Neither XIAP nor p63 were detected in normal lung alveolar cells. All seven AHs were negative for XIAP and negative or focally positive for p63. All eight AAHs were positive for XIAP and displayed p63 positivity in scattered cells. All BACs displayed XIAP positivity, which ranged from focal/weak to diffuse/strong. p63 was negative in seven and focally positive in two of nine BACs. Twelve of 13 WDACs showed XIAP positivity in a similar pattern to BAC; all were negative for p63. One aberrant case diagnosed on H & E as WDAC was negative for XIAP but strongly positive for p63. Significant XIAP expression appears to be useful for distinguishing AAH from AH. Commonality of XIAP staining in AAH, BAC and WDAC supports the possibility that AAH may be a pre-malignant lesion. The rarity of p63 expression confirms previous reports and supports a nonbronchial histogenesis of these entities. In contrast, diffuse p63 staining may facilitate the identification of rare cases that may have been misclassified as alveolar in origin based on morphology but may be of BRC origin.  相似文献   
43.
44.
Summary Gaeumannomyces graminis var.graminis andtritici were transformed to benomyl resistance using pBT3, a plasmid encoding fungicide-resistant -tubulin. Either circular or linear plasmid DNA producedG. graminis var.graminis transformants in which plasmid DNA was integrated into the fungal genome. There was no evidence for autonomous plasmid replication in any of the transformants examined. 4/11 linear DNA transformants had a single plasmid copy, whereas 8/9 circular DNA transformants had multiple copies of the plasmid. Integration of transforming DNA occurred by nonhomologous recombination in all (20/20) of these transformants.  相似文献   
45.
46.
We have previously demonstrated that p100H mutant mice, which lack a functional Sox6 gene, exhibit skeletal and cardiac muscle degeneration and develop cardiac conduction abnormalities soon after birth. To understand the role of Sox6 in skeletal muscle development, we identified muscle-specific genes differentially expressed between wild-type and p100H mutant skeletal muscles and investigated their temporal expression in the mutant muscle. We found that, in the mutant skeletal muscle, slow fiber and cardiac isoform genes are expressed at significantly higher levels, whereas fast fiber isoform genes are expressed at significantly lower levels than wild-type. Onset of this aberrant fiber type-specific gene expression in the mutant coincides with the beginning of the secondary myotube formation, at embryonic day 15-16 in mice. Together with our earlier report, demonstrating early postnatal muscle defects in the Sox6 null-p100H mutant, the present results suggest that Sox6 likely plays an important role in muscle development.  相似文献   
47.
The isthmo-optic nuclei (ION) and ectopic neurons, which constitute the centrifugal visual system (CVS), are thought to be cholinoceptive and nitrergic. However, it is not clear which neurons express these markers, namely the ones that project to the retina rather than in neurons that only participate in a local circuit. Therefore, to characterize the neurochemical patterns of the centrifugal visual system in the post-hatched chick, retinopetal cells of the isthmo-optic nuclei and the ectopic region were identified via immunolabeling for cholera toxin, a neuronal tracer, which has been injected in the ocular globe. Then, double labeled with acetylcholinesterase histochemistry to reveal cholinergic synapses, or NADPH-diaphorase histochemistry as a nitrergic marker. Briefly, acetylcholinesterase activity was present mainly in cholera toxin labeled cell bodies of the isthmo-optic nucleus and the ectopic region indicating that retinal projecting neurons of centrifugal visual system comprise a cholinoceptive pathway. On the other hand, NADPH-diaphorase histochemistry was present in the neuropile and sparse cell bodies inside of the isthmo-optic nucleus and in ectopic neurons which were not cholera toxin positive suggesting their role in an intrinsic circuit of the centrifugal visual system. These data support the idea that these two neurochemical systems are present in distinct neuronal populations in the centrifugal visual system.  相似文献   
48.
Prevention Science - Screening is an essential prevention practice for a number of health conditions. However, screening coverage remains generally low. Studies that investigate determinants of...  相似文献   
49.
Maternal and Child Health Journal - Low birthweight (LBW) is a significant public health problem in sub-Saharan Africa and LBW in rural Zambia is high. Our study explored the prevalence of LBW for...  相似文献   
50.
Prevention Science - The NAMWEZA intervention was implemented, using a ten-session group format, to build skills targeting psychosocial vulnerabilities and enhancing HIV prevention among people...  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