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   378493篇
  免费   24854篇
  国内免费   2803篇
耳鼻咽喉   5184篇
儿科学   8204篇
妇产科学   10081篇
基础医学   53124篇
口腔科学   11805篇
临床医学   30116篇
内科学   78306篇
皮肤病学   8554篇
神经病学   27203篇
特种医学   13913篇
外国民族医学   82篇
外科学   60578篇
综合类   9957篇
现状与发展   1篇
一般理论   64篇
预防医学   17431篇
眼科学   9454篇
药学   30984篇
  1篇
中国医学   2194篇
肿瘤学   28914篇
  2021年   2614篇
  2019年   2724篇
  2018年   4517篇
  2017年   3430篇
  2016年   3520篇
  2015年   4016篇
  2014年   5694篇
  2013年   7377篇
  2012年   10028篇
  2011年   10202篇
  2010年   6193篇
  2009年   5838篇
  2008年   9447篇
  2007年   10292篇
  2006年   10199篇
  2005年   9271篇
  2004年   8777篇
  2003年   8511篇
  2002年   8186篇
  2001年   28272篇
  2000年   28784篇
  1999年   23668篇
  1998年   5165篇
  1997年   4255篇
  1996年   3829篇
  1995年   3487篇
  1994年   3104篇
  1993年   2845篇
  1992年   16048篇
  1991年   14814篇
  1990年   14160篇
  1989年   13965篇
  1988年   12583篇
  1987年   12066篇
  1986年   11110篇
  1985年   10322篇
  1984年   6913篇
  1983年   5601篇
  1982年   2720篇
  1979年   5481篇
  1978年   3348篇
  1977年   2972篇
  1975年   2642篇
  1974年   3065篇
  1973年   2866篇
  1972年   2828篇
  1971年   2773篇
  1970年   2512篇
  1969年   2545篇
  1968年   2250篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
Fluorescent model substances of increasing lipophilicity (Oregon Green) 488, Bodipy, FL C5 and Bodipy 564/570 C5) were selected to enable the visualization in the skin using confocal laser scanning microscopy. After measuring the penetration for 18 h, the nonfixed human scalp skin was imaged from the bottom parallel to the stratum corneum and in a cross-section view perpendicular to the skin surface. The images were evaluated by calculating relative accumulation values for different penetrants. The studies indicate that the penetrated amount is highest for Bodipy FL C5 (medium lipophilicity) and lowest for Bodipy 564/570 C5 (high lipophilicity) whereas Bodipy 564/570 C5 (high lipophilicity) reveals the highest relative accumulation in parts of the hair follicle compared to Oregon Green 488 (low lipophilicity). The addition of 30% (v/v) ethanol to the donor phase of substance with a low lipophilicity increases the follicular delivery. From our results we conclude that delivery to the hair follicle can be improved by increasing the drugs lipophilicity and optimizing the composition of the donor phase. However, no conclusion can be drawn about the actual route of transport to the hair follicle.  相似文献   
162.
163.
A 70-year-old woman developed left hypoglossal nerve palsy, a right hemiparesis sparing the face, and a typical left Wallenberg's syndrome. These symptoms resulted from a lesion in the left half of the medulla oblongata, suggesting Babinski-Nageotte syndrome, a rare cerebrovascular disease. This is the first case of ischemic infarction in the territory of the left vertebral artery and posterior inferior cerebellar artery demonstrated on magnetic resonance imaging. Severe bilateral lesions of the distal vertebral arteries demonstrated on digital subtraction angiography may have contributed to the development of this syndrome.  相似文献   
164.
The presence of cytochrome P-45011 beta in rat brain was studied by immunohistochemistry using polyclonal rabbit antibodies raised against purified bovine adrenocortical P-45011 beta, which is involved in the steroid 11 beta-hydroxylation and glucocorticoid formation. The results showed that cytochrome P-45011 beta immunoreactivity is selectively localized to the tracts of myelinated fibers throughout the brain. The specificity of immunohistochemical stainings with P-45011 beta antibodies was established by control tests including nonimmune rabbit immunoglobulin Gs and P-45011 beta antibodies absorbed with purified antigen. Western immunoblots of homogenates from different brain areas with P-45011 beta antibodies, together with biochemical enzymatic assays for cytochrome P-45011 beta monooxygenase activity in these homogenates, confirmed the selective localization of this enzyme observed with immunohistochemistry. Cytochrome P-45011 beta and 11 beta-hydroxylase activity were detected in a homogenate from the cortical white matter (brain area rich in myelinated fibers) as in that from the rat adrenal, but were not detectable in a homogenate from the cerebral cortex (brain area poor in myelinated fibers). Furthermore, quantitation of the P-45011 beta bands on the immunoblots by the areal density revealed that the cortical white matter contains approximately 1.4 pmol of cytochrome P-45011 beta/mg of tissue protein, the value of which was about one sixth of the corresponding value estimated in the rat adrenal. This relatively high content of cytochrome P-45011 beta was also reflected in a relatively high level of 11 beta-hydroxylase activity measured in a homogenate of this brain area by biochemical enzymatic assays using [4-14C]-11-deoxycorticosterone.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
165.
In this paper, the rare earth magnets (Nd-Fe-B) were used for treatment of cross-bite of anterior teeth. Eight patients were selected. In an attempt to achieve the labial movement of upper anterior teeth, removable appliance with repelling magnetic force were used. The treatment results are satisfactory. The following facts were discussed: (1) the direction of the repelling magnetic force can be controlled well with the double rails; (2) the time for treatment was short and there was no manifestation of unfavorable reaction and (3) no adverse bioeffects have been reported in regard to the use of this kind of device.  相似文献   
166.
Addison's disease is rarely caused by metastatic cancer. We report a unique case of hypoadrenalism owing to metastatic transitional cell carcinoma of the bladder. The relevant literature is reviewed.  相似文献   
167.
Although the human tumor clonogenic assay (HTCA) is extremely reliable in determining clinical correlations, it is a complicated process requiring considerable time in order to obtain results. Thus, an experimental study on cytopathologic observation (cytologic assay) and comparative evaluation between it and HTCA were performed in order to establish a more rapid and accurate drug sensitivity test. Materials included Colon 26, a cell line established in our department, malignant effusion and surgical specimens. In carrying out HTCA according to the Hamburger-Salmon method, the cell suspension samples following exposure to anti-tumor agents (MMC, L-PAM, ADM, CDDP) were cultivated in test tubes for 3-8 hours and stained by the Papanicolaou and Giemsa methods. According to Tokita's criteria, when cellular changes showed as nuclear pyknosis and nuclear destruction were found to have increased significantly in comparison with a control group, the cells were judged to be sensitive. Very similar and parallel results were obtained between HTCA and cytologic assay in this study, with a significant correlation. Cytologic assay was proved to be an easy, rapid and accurate method for testing drug sensitivity and its clinical application can be expected in the future.  相似文献   
168.
IgG-maleimide peroxidase, Fab'-maleimide peroxidase, polymer and monomer types of Fab'-periodate peroxidase were prepared from an antibody against rat lipoamide dehydrogenase, a component of the pyruvate dehydrogenase complex which is located in mitochondria. They were examined for immunohistochemical staining of the rat kidney. Fab'-maleimide peroxidase was the best for staining mitochondrial protein. IgG-maleimide peroxidase and the monomer type of Fab'-periodate peroxidase had the same intensity of staining. The polymer type of Fab'-periodate peroxidase could not stain the lipoamide dehydrogenase.  相似文献   
169.
170.
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