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   2660篇
  免费   135篇
  国内免费   14篇
耳鼻咽喉   12篇
儿科学   36篇
妇产科学   15篇
基础医学   365篇
口腔科学   71篇
临床医学   209篇
内科学   586篇
皮肤病学   37篇
神经病学   234篇
特种医学   67篇
外科学   326篇
综合类   18篇
预防医学   106篇
眼科学   8篇
药学   379篇
中国医学   11篇
肿瘤学   329篇
  2022年   25篇
  2021年   42篇
  2018年   28篇
  2017年   28篇
  2016年   23篇
  2015年   23篇
  2014年   38篇
  2013年   36篇
  2012年   80篇
  2011年   82篇
  2010年   34篇
  2009年   45篇
  2008年   74篇
  2007年   86篇
  2006年   79篇
  2005年   84篇
  2004年   113篇
  2003年   86篇
  2002年   107篇
  2001年   99篇
  2000年   93篇
  1999年   118篇
  1998年   43篇
  1997年   37篇
  1996年   29篇
  1995年   23篇
  1994年   23篇
  1992年   79篇
  1991年   86篇
  1990年   88篇
  1989年   70篇
  1988年   82篇
  1987年   58篇
  1986年   69篇
  1985年   60篇
  1984年   34篇
  1983年   51篇
  1982年   25篇
  1981年   42篇
  1980年   41篇
  1979年   55篇
  1978年   37篇
  1977年   28篇
  1976年   23篇
  1975年   28篇
  1974年   38篇
  1973年   32篇
  1972年   23篇
  1971年   27篇
  1968年   21篇
排序方式: 共有2809条查询结果,搜索用时 31 毫秒
61.
Burst patterns in the digastric, mylohyoid, and masseter muscles and the resultant jaw movement orbits during chewing and swallowing were investigated in the freely behaving rabbit. Activities in the posterior mylohyoid fibers consisted of two continuous bursts. Peaks in the first burst of the posterior fibers occurred in the middle part of opening and preceded the digastric burst. Peaks in the second burst occurred in the final part of opening and coincided with those in the working side of the digastric burst. After removal of the bilateral digastric muscles, the gape size during chewing was largely reduced in the final part of opening and in the early part of closing. The results suggest that (a) the digastric may have a role in opening the mandible widely beyond the rest position but may not have a major role in the control of the horizontal (mediolateral) jaw movement, (b) the posterior mylohyoid fibers may have a function as an elevator of the tongue in the early part of opening, and (c) the posterior mylohyoid fibers may have a function as a depressor of the jaw in the late part of opening. Electromyographic burst in the mylohyoid muscle began with marked activity in the mid-closing phase. The results support a role for the mylohyoid muscle as a leading muscle of swallowing. Swallowing events in the rabbit are easily distinguished from the activities of the mylohyoid muscle and the thyrohyoid muscle.  相似文献   
62.
Spontaneous echo contrast in the descending aorta (DA-SEC) was examined as a possible risk factor for cerebral thromboembolism. In 19 patients (10 males, 9 females) in the chronic stage of cerebral infarction, abnormal findings by transesophageal echocardiography, flow dynamics of the common carotid artery (CCA), and hemostatic factors including blood coagulation and fibrinolysis were investigated. In nine patients, DA-SEC was detected, and SEC in left atrium (LA-SEC) was detected in nine patients. The DA-SEC positive group showed decreased blood-flow velocity (BFV) in bilateral CCA, high levels of thrombin-antithrombin III complex (TAT) and prothrombin fragment 1.2 (F1+2), a decrease in platelet count and a slight increase in D-dimer, which means an activated state of thrombin generation and resulting fibrinolysis, compared to the DA-SEC negative group. On the other hand, the LA-SEC positive group showed normal BFV in CCA and only a slight increase in D-dimer. We conclude that the condition producing DA-SEC is a stronger risk factor for cerebral infarction than that producing LA-SEC.  相似文献   
63.
Sixty-four patients with liver metastases from colorectal cancer were studied to clarify the characteristics of the regional spread of liver metastases (secondary invasive factors) and the effects of major anatomical hepatic resection with lymph node dissection on reducing liver recurrence. No secondary invasive factors, i.e., lymph node metastasis, portal or hepatic vein involvement, bile duct involvement, micrometastasis, and direct invasion, were observed in patients with liver metastases less than 3 cm in diameter (5-year survival rate; 100%). Secondary invasive factors were seen in 19.2% of the patients with liver metastases from 3 cm to less than 6 cm (5-year survival rate; 28.7%), and in 45.2% of those with liver metastases 6 cm and over (5-year survival rate; 14.6%). Secondary invasive factors were noted in 45% of the patients with recurrence in the remmant liver. Although 31% of all 64 patients exhibited secondary invasive factors, major anatomical hepatic resection with lymph node dissection achieved a low liver recurrence rate of 31.3%. In conclusion, considering the risks attributed to secondary invasive factors, major anatomical hepatic resection with lymph node dissection is an appropriate surgical procedure for patients with liver metastases exceeding 3 cm in diameter.  相似文献   
64.
A lectin histochemistry approach was adopted for comparative assessment of a colon cancer risk. Binding of Ulex europaeus agglutinin-I (UEA-I), peanut agglutinin (PNA), Griffonia simplicifolia agglutinin-II (GSA-II), and Dolichos biflorus agglutinin (DBA) was investigated in tumor and background tissue from a total of 34 adenoma and 44 cancer patients and compared with reaction patterns in control and familial adenomatous pplyposis (FAP) patients. Adenoma patients with UEA-I positive rectal mucosa were found to have a 33.3 percent familial history of large bowel cancer, which was significantly higher (P <0.05) than the respective 4.0 percent figure for patients with negative rectal mucosa. In the cancer patients, an even stronger correlation was noted, with a 63.2 percent UEA-I positive family history association being recorded, as opposed to 4.0 percent in the negative rectal mucosa patients (P <0.01). Thus, the results suggest that, apparently, normal rectal background mucosa of individuals genetically at high risk for colon and rectal cancer demonstrates a specific lectin binding ability similar to that of FAP patients and that the simple method using UEA-I staining of rectal biopsy specimens can be of practical use in identification of high-risk colorectal cancer.  相似文献   
65.
The in vitro metabolism of (‐)‐cis‐ and (‐)‐trans‐rose oxide was investigated using human liver microsomes and recombinant cytochrome P450 (P450 or CYP) enzymes for the first time. Both isomers of rose oxide were incubated with human liver microsomes, and the formation of the respective 9‐oxidized metabolite were determined using gas chromatography‐mass spectrometry (GC‐MS). Of 11 different recombinant human P450 enzymes used, CYP2B6 and CYP2C19 were the primary enzymes catalysing the metabolism of (‐)‐cis‐ and (‐)‐trans‐rose oxide. CYP1A2 also efficiently oxidized (‐)‐cis‐rose oxide at the 9‐position but not (‐)‐trans‐rose oxide. α‐Naphthoflavone (a selective CYP1A2 inhibitor), thioTEPA (a CYP2B6 inhibitor) and anti‐CYP2B6 antibody inhibited (‐)‐cis‐rose oxide 9‐hydroxylation catalysed by human liver microsomes. On the other hand, the metabolism of (‐)‐trans‐rose oxide was suppressed by thioTEPA and anti‐CYP2B6 at a significant level in human liver microsomes. However, omeprazole (a CYP2C19 inhibitor) had no significant effects on the metabolism of both isomers of rose oxide. Using microsomal preparations from nine different human liver samples, (‐)‐9‐hydroxy‐cis‐ and (‐)‐9‐hydroxy‐trans‐rose oxide formations correlated with (S)‐mephenytoin N‐demethylase activity (CYP2B6 marker activity). These results suggest that CYP2B6 plays important roles in the metabolism of (‐)‐cis‐ and (‐)‐trans‐rose oxide in human liver microsomes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
66.
Six mycobacterial strains which were isolated and identified with some suspicions in five hospitals in Japan were retested for their biological and biochemical characteristics for correct identification at the Department of Microbiology and Immunology, Shimane Medical University. One strain originally classified as Group IV Mycobacterium, and two unidentified strains were presently identified as Mycobacterium nonchromogenicum complex. Two strains originally identified as M. xenopi were identified by us as M. szulgai and M. avium complex, respectively. Finally, one strain originally identified as M. phlei was identified by us as M. fortuitum. In these cases, inexactly controlled examinations for growth rate, growth at 45 degrees C, Tween 80 hydrolysis, and pigment production or lack of tests for certain key characters of a given organism seemed to be main causes of initial incorrect identification.  相似文献   
67.
68.
Eighteen patients with active Crohn's disease were treated with one leukocytapheresis session per week for a five-week intensive therapy, decreasing to one leukocytapheresis session per month for five sessions of initial maintenance therapy. Nutritional indices, inflammatory reactions, flow cytometry profiles, and cytokine production were also assessed before and after the intensive and initial maintenance therapy. Nine of the patients (50%) attained remission at the end of the intensive therapy. The nine non-remission patients had exhibited longer periods of suffering and more severely affected sites prior to the therapy. In 14 of 18 patients (77.8%), the nutritional indices, Internal Organization of Inflammatory Bowel Disease (IOIBD) score and Crohn's Disease Activity Index (CDAI) improved from the pretherapy levels, but only the remission group (50%) showed improvement in C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). The remission group showed significantly higher pretherapy CD4+ CD45+ cell ratios and interleukin-2 (IL-2) production than the non-remission group, and significantly lower activated cells.  相似文献   
69.
The expression of blood group-related antigens of the Lewis system in normal gastric mucosa, intestinal metaplasia, gastric adenoma, and gastric carcinoma was examined. Ninety-five percent of normal foveolar epithelial samples stained positive for Lewisb antigen, whereas only 10.0% expressed Lewisa antigen. In contrast, intestinal metaplasia specimens had increased Lewisa antigen expression and slightly decreased Lewisb antigen expression. A similar pattern of Lewisa and Lewisb expression was observed in gastric adenomas and intestinal type adenocarcinomas. Lewisx and Lewisy were detected in all normal deep glands, but were not expressed in the majority of intestinal metaplasia specimens. In addition, only 20–40% of gastric adenomas and gastric carcinomas expressed Lewisx and Lewisy antigens. These changes in Lewis antigen expression in intestinal metaplasia, adenomas, and intestinal type adenocarcinomas suggest that altered expression of Lewis blood group-related antigens may correlate with cell transformation processes.  相似文献   
70.
Vipoma of the Pancreas Complicating Ulcerative Colitis   总被引:2,自引:0,他引:2  
We report a case of vipoma of the pancreas in conjunction with ulcerative colitis in a 20-yr-old woman. Twenty months after the onset of ulcerative colitis, the patient complained of watery diarrhea and was found to have an electrolyte disorder. A pancreatic tumor was detected by ultrasonography and computed tomography, along with an elevation of serum vasoactive intestinal polypeptide (VIP). The secretory diarrhea diminished dramatically, and the serum VIP level decreased into the normal range immediately after resection of the pancreatic tumor. Immunohistochemical staining revealed a pancreatic vipoma. Despite removal of the vipoma, she underwent restorative proctocolectomy and ileal J-pouch anal anastomosis 2 yr later due to progression of the ulcerative colitis. Postoperative course was uneventful, with excellent functional results. Knowledge of this rare condition accompanying ulcerative colitis may help in the management of the patient with an atypical clinical course.  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