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   38461篇
  免费   2008篇
  国内免费   227篇
耳鼻咽喉   351篇
儿科学   548篇
妇产科学   424篇
基础医学   5064篇
口腔科学   1105篇
临床医学   2519篇
内科学   9529篇
皮肤病学   966篇
神经病学   2689篇
特种医学   1441篇
外科学   6493篇
综合类   206篇
一般理论   1篇
预防医学   1222篇
眼科学   746篇
药学   2929篇
中国医学   49篇
肿瘤学   4414篇
  2023年   198篇
  2022年   389篇
  2021年   731篇
  2020年   448篇
  2019年   509篇
  2018年   692篇
  2017年   611篇
  2016年   636篇
  2015年   702篇
  2014年   928篇
  2013年   1165篇
  2012年   1781篇
  2011年   1964篇
  2010年   1130篇
  2009年   1001篇
  2008年   1713篇
  2007年   1772篇
  2006年   1791篇
  2005年   1829篇
  2004年   1745篇
  2003年   1744篇
  2002年   1698篇
  2001年   1353篇
  2000年   1370篇
  1999年   1271篇
  1998年   482篇
  1997年   405篇
  1996年   378篇
  1995年   355篇
  1994年   306篇
  1993年   297篇
  1992年   869篇
  1991年   754篇
  1990年   757篇
  1989年   732篇
  1988年   736篇
  1987年   648篇
  1986年   632篇
  1985年   615篇
  1984年   408篇
  1983年   334篇
  1982年   161篇
  1980年   149篇
  1979年   328篇
  1978年   212篇
  1977年   156篇
  1975年   156篇
  1974年   213篇
  1973年   152篇
  1972年   167篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
Photoreactive (meth)acrylate monomers having mesogenic groups based on 4-hexyloxy-4′-(3-methyl-2-butenyloxy)biphenyl and 4-hexyloxy-4′-(2-butenyloxy)biphenyl were synthesized. Methacrylate monomers ( 3c, d ) and acrylate monomer having 3-methyl-2-butenyloxy group ( 3b ) were polymerized by free radical mechanism; the acrylate monomer having 2-butenyloxy group ( 3a ) caused gelation during the polymerization. To obtain photoreactivity, 4-benzoylphenyl (meth)acrylates were radically copolymerized with monomers 3b and 3d . Thermal behavior of (co)polymers was determined by differential scanning calorimetry, polarized optical microscopy and temperature-controlled X-ray analysis. (Co)polymers showed liquid-crystalline behaviour with nematic and smectic phases. UV-irradiation was used to photochemically crosslink copolymer films, and the resultant films were insoluble in organic solvents. The uniaxially oriented copolymer thin film was photo-crosslinked and showed thermally stable orientation.  相似文献   
22.
23.
We report the case of an infant with a cerebellar astrocytoma that showed marked calcification within only 6 months. In general, only slow-growing tumors tend to calcify. To our knowledge, no other case of such rapid calcification in cerebellar astrocytoma has been reported.  相似文献   
24.
Immunopathogenicity of trypsin-solubilized or non-solubilized renal tubular basement membrane (TBM) of the Lewis (LEW) rat was investigated. Autoimmune tubulointerstitial nephritis (TIN) was induced in BALB/c mice by immunization with trypsin-solubilized LEW rat TBM, while immunization with non-solubilized TBM did not produce the disease. Based on this preliminary experiment we studied the characterization of immunogenic and nephritogenic TBM antigen of the LEW rat. TIN was characterized by severe mononuclear cell infiltrates with multi-nucleated giant cells in the interstitium, tubular destruction and intensive IgG and C3 deposits along the TBM. Anti-TBM antisera and eluate from the nephritic mouse kidneys reacted with the TBM of normal LEW rat kidney by immunofluorescence. LEW rat TBM was also detected immunofluorescently by using antisera from BALB/c mice immunized with autologous trypsin-solubilized TBM. A competitive inhibition test revealed a higher titer of anti-TBM antibody in the eluate than in the adsorption-treated antisera per microgram IgG. Immunoblotting showed one reactive band with a molecular weight of 45,000 daltons, and the blotting patterns in tryptic TBM of the Brown Norway (BN) and LEW rats appeared similar. Amino acid analysis of nephritogenic LEW rat tryptic TBM showed that it contained no hydroxyproline and hydroxylysine, suggesting that this TBM preparation was not collagenous. These findings suggest that tryptic digestion contributes to the release of nephritogenic antigen from the LEW rat TBM and that this antigen system might participate in the immune system involved in the anti-TBM associated TIN that is well known to be induced by non-digested TBM of TBM antigen positive animals.  相似文献   
25.
26.
This is a case report on a patient with double cancer of kidney and urinary bladder. The patient was a 65-year-old female, and she was admitted with the chief complaint of gross hematuria and right flank pain. After careful examinations, she was diagnosed with right nonfunctioning kidney caused by invasive bladder cancer. Computerized tomography incidentally revealed a mass in the upper pole of the left kidney. Selective left renal arteriography showed stretched arteries and irregularity and tortuosity of the smaller vessels. She was diagnosed with double cancer of bladder and left kidney. Owing to the damage of the right renal function, left partial nephrectomy, total cystectomy, right nephroureterectomy and left ureterocutaneostomy were performed. According to DMSA scintigraphy measured 15 days later, the uptake value of the left kidney was 13.25%, compared to the preoperative value of 25.62%. To date, this case is 36th reported case in Japan.  相似文献   
27.
The matrix metalloproteinase matrilysin (MMP-7) is a member of the matrix metallo-proteinase gene family, which is believed to play an important role in tumor invasion and metastasis. We have previously found that matrilysin mRNA is specifically expressed in colorectal cancers and adenomas and that its message is localized in the tumor cells themselves. We examined the effects of activated Ki-ras oncogene on the expression of matrilysin in colon cancer cells. We showed that both mRNA and the enzymatic activity of matrilysin were induced by the introduction of activated Ki-ras into SW1417 colon cancer cells. To understand the mechanisms regulating this induction, we analyzed alterations of AP-1 activity induced by activated Ki-ras, using the chloramphenicol acetyltransferase assay. AP-1 activity in SW1417 cells expressing activated Ki-ras was higher than that in control cells. The gel-shift assay also showed higher levels of AP-1 binding protein in SW1417 cells expressing activated Ki-ras than those in control cells. Our results suggest that activated Ki-ras may play a role in inducing expression of matrilysin through an AP-1-dependent pathway in colon cancer cells.  相似文献   
28.
29.
30.
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