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   481篇
  免费   30篇
  国内免费   1篇
耳鼻咽喉   2篇
儿科学   5篇
妇产科学   6篇
基础医学   62篇
口腔科学   5篇
临床医学   62篇
内科学   103篇
皮肤病学   8篇
神经病学   58篇
特种医学   18篇
外国民族医学   3篇
外科学   62篇
综合类   5篇
预防医学   41篇
眼科学   2篇
药学   49篇
肿瘤学   21篇
  2023年   2篇
  2022年   3篇
  2021年   12篇
  2020年   4篇
  2019年   8篇
  2018年   6篇
  2017年   5篇
  2016年   6篇
  2015年   3篇
  2014年   12篇
  2013年   11篇
  2012年   21篇
  2011年   20篇
  2010年   19篇
  2009年   16篇
  2008年   39篇
  2007年   39篇
  2006年   39篇
  2005年   28篇
  2004年   21篇
  2003年   20篇
  2002年   23篇
  2001年   14篇
  2000年   13篇
  1999年   15篇
  1998年   7篇
  1997年   6篇
  1996年   3篇
  1995年   3篇
  1993年   2篇
  1992年   8篇
  1991年   6篇
  1990年   7篇
  1989年   7篇
  1988年   8篇
  1987年   5篇
  1986年   8篇
  1985年   10篇
  1983年   4篇
  1981年   3篇
  1978年   2篇
  1977年   2篇
  1973年   3篇
  1972年   3篇
  1971年   2篇
  1970年   3篇
  1969年   3篇
  1967年   1篇
  1962年   2篇
  1956年   1篇
排序方式: 共有512条查询结果,搜索用时 15 毫秒
1.
2.
3.
Five years after treatment in a controlled trial, in which all had received self-exposure homework, a group of 40 agoraphobic outpatients retained marked improvement in agoraphobia, mood, and free-floating anxiety. Frequency of spontaneous panics decreased as much in those who had placebo and self-exposure as in those who received imipramine and self-exposure. Few patients, however, were completely well at 5 years and over half had received further treatment for agoraphobia during the follow-up. Patients who were still highly phobic at the end of the clinical trial were more often prescribed psychotropic medication during follow-up and remained phobic at 5 years. Phobic improvement had generalized more in those patients with very low than in those with moderate pretreatment Hamilton depression scores. Frequency of initial spontaneous panics did not predict outcome. Improvement in agoraphobia was associated with improved marital adjustment. Those who began with the best marital, work, and social adjustment were more improved in their phobias 5 years later.  相似文献   
4.
Thyroid function tests were performed on 16 clinically euthyroid patients with end-stage renal failure undergoing regular haemodialysis or continuous ambulatory peritoneal dialysis and compared with 8 healthy subjects. The patient groups were carefully matched, especially regarding relative duration of dialysis (mean of 24 months). Total serum thyroxine, total triiodothyronine, free thyroxine, free triiodothyronine and reverse triiodothyronine were significantly lower in both patient groups than control. The thyrothrophin response to the standard thyrotrophin-releasing hormone test was delayed and blunted. Using a novel concentration technique we measured loss of T4 in peritoneal dialysate effluent and found it to be approximately 10% of daily thyroidal T4 release.  相似文献   
5.
The psychiatric investigation of a sample of 101 epileptic patients (65 temporal lobe epileptics (TLE) and 36 non-TLE) through various methods of evaluation, showed that only a minority of TLE with DSM-III diagnoses of Organic Brain Syndromes had severe psychopathology and manifested some personality traits. Thus, these patients seem to be differentiated from the rest of epileptics, TLE and non-TLE, who had quite "benign" psychological problems, if at all. It is quite probable that this sub-group of TLE could be the main instigators and perpetrators of the "bad image" of epileptics. The findings are discussed in relation to the pertinent literature and some hypotheses are offered for their explanation.  相似文献   
6.
When Marburg virus (MBGV) nucleoprotein (NP) is expressed in insect cells, it binds to cellular RNA and forms NP-RNA complexes such as insect cell-expressed nucleoproteins from other nonsegmented negative-strand RNA viruses. Recombinant MBGV NP-RNA forms loose coils that resemble rabies virus N-RNA. MBGV NP monomers are rods that are spaced along the coil similar to the nucleoprotein monomers of the rabies virus N-RNA. High salt treatment induces tight coiling of the MBGV NP-RNA, again a characteristic observed for other nonsegmented negative-strand virus N-RNAs. Electron microscopy of fixed Marburg virus particles shows that the viral nucleocapsid has a smaller diameter than the free, recombinant NP-RNA. This difference in helical parameters could be caused by the interaction of other viral proteins with the NP-RNA. A similar but opposite phenomenon is observed for rhabdovirus nucleocapsids that are condensed by the viral matrix protein upon which they acquire a larger diameter. Finally, there appears to be an extensive and regular protein scaffold between the viral nucleocapsid and the membrane that seems not to exist in the other negative-strand RNA viruses.  相似文献   
7.
BACKGROUND: Asthma and rhinitis often coexist, and there is evidence to suggest that they have similar histopathologic features. OBJECTIVE: To examine whether the inflammatory infiltration in the nasal mucosa in rhinitis is affected by the presence of asthma and allergy. METHODS: Nasal mucosa biopsy samples were collected from 44 individuals: 18 with rhinitis and asthma (9 allergic and 9 nonallergic), 16 with rhinitis and no asthma (8 allergic and 8 nonallergic), and 10 nonallergic control subjects. The alkaline phosphatase-anti-alkaline phosphatase method was applied to 6-microm-thick cryostat sections using monoclonal antibodies against T cells (CD4 and CD8) and eosinophils (EG2). Slides were counted blindly, and results are expressed as cells per high-power field. RESULTS: Eosinophil counts were higher in the nasal mucosa of rhinitic patients vs controls. No differences in cellular infiltration were detected between rhinitic patients with and without asthma or between allergic and nonallergic patients. A trend toward higher CD4+ T-cell counts in the nasal mucosa of rhinitic patients was observed, whereas no differences were noted in CD8+ T-cell infiltration among the groups. CONCLUSION: Inflammatory infiltration, characterized by the presence of eosinophils and CD4+ T cells, was similar in the nasal mucosa in noninfectious rhinitis irrespective of the presence of asthma or the allergic status of the patient.  相似文献   
8.
KG111 is a mutant of herpes simplex virus (HSV), strain KOS, that exhibits temperature-dependent drug resistance. For example, it is almost as resistant as a thymidine kinase (tk)-deficient virus at 39 degrees, but is relatively sensitive to acyclovir at 34 degrees, Using marker transfer techniques, we have mapped the mutation conferring temperature-dependent drug resistance in KG111 to the 5' portion of the tk gene. Sequencing of this region revealed an amber mutation at codon 44, which lies between the first and second methionine codons of the tk polypeptide. This mutation is identical to that found in TK4, an HSV mutant derived from Cl 101 (L. Haarr et al., 1985, J. Virol. 56, 512-519). Analyses of immunoprecipitated tk proteins from KG111- and TK4-infected cells showed that KG111 and TK4 do not synthesize full-length tk polypeptides, but instead produce a truncated form of the protein. Small amounts of a similar truncated tk polypeptide are also produced in wild-type-infected cells and are thought to arise from initiation at a downstream AUG. The relative amounts and size of the mutant tk proteins compared with those of the wild-type are consistent with the amber mutation eliminating translation of full-length polypeptide and causing a four- to fivefold increase in the utilization of downstream AUG codons for initiation. The truncated polypeptides specified by KG111 and TK4 are less stable than the full-length polypeptide at 39 degrees, which may contribute to the conditional drug-resistant phenotype. On the other hand, the truncated polypeptides normally expressed by wild-type virus at low levels and the more highly expressed truncated tk polypeptides from a deletion mutant are relatively stable at 39 degrees. These results suggest that stability of the truncated tk polypeptide is influenced by the amount of tk present.  相似文献   
9.
The strong association of human papillomavirus (HPV) and cervical cancer makes it important to study HPV detection methods that may play a role in cervical cancer screening. We compared two DNA methods that are commonly used for HPV research in the United States: the MY09/MY11 L1 consensus primer PCR-based test and the first-generation Hybrid Capture tube method (HCT). Laboratory assays by each method were performed with 596 cervicovaginal specimens collected from participants in a large cohort study conducted in Portland, Oreg. Included were 499 specimens from women whose cytology was normal and 97 specimens from women with squamous intraepithelial lesions (SILs). The overall HPV DNA positivity for known types was 22.5% by PCR compared to 13.6% by HCT. When the analysis was restricted to the 14 HPV types detectable by both methods, the sensitivity of HCT, with PCR used as the standard for HPV status, was higher for specimens from women with concurrent SILs (81.0%) than for specimens from women with normal cytology (46.7%). Among specimens testing positive by both methods, 97.2% of the time the two methods agreed on whether specimens were positive for cancer-associated HPV types. Both of these HPV test methods provide information that supplements the information provided by the Pap smear. The PCR method has higher analytic sensitivity than HCT in detecting HPV, but HCT may be helpful in identifying women with concurrent SILs.  相似文献   
10.
A methodologic study was performed to compare the polymerase chain reaction (PCR) and Southern blot hybridization, two commonly used testing strategies for the detection of human papillomavirus (HPV) infection. Three laboratories tested masked aliquots of exfoliated cervical cell specimens obtained from 120 women by cervicovaginal lavage. The study population included 32 women with condylomatous atypia or cervical intraepithelial neoplasia and 88 control women with no known history of cervical neoplasia. Two laboratories used PCR with different sets of consensus primers for HPV detection. The third laboratory used low-stringency Southern blot hybridization to identify all HPV types, followed by high-stringency Southern and/or dot blot hybridization to confirm specific HPV types. One of the PCR primer sets detected HPV types with a differential efficiency that was not predicted by analysis of DNA sequences or direct testing of HPV-containing plasmids. In contrast, the second PCR primer set was shown to be a much broader consensus system, detecting the same HPV types as Southern blotting, though requiring much less clinical specimen. Over 80% of women with cervical intraepithelial neoplasia or condylomatous atypia were found to be HPV infected both by Southern blotting and by the second PCR primer set. Among the control women, 11% were HPV positive by Southern blotting, while 31% were positive with the second set of primers. Most of the HPV infections found only by PCR were not due to HPV type 6, 11, 16, 18, 31, 33, or 45. These known HPV types were uncommon among normal women in the study population, even as determined by the PCR method.  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