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   810篇
  免费   62篇
  国内免费   2篇
耳鼻咽喉   1篇
儿科学   13篇
妇产科学   26篇
基础医学   55篇
口腔科学   9篇
临床医学   62篇
内科学   232篇
皮肤病学   6篇
神经病学   24篇
特种医学   65篇
外科学   184篇
综合类   7篇
预防医学   50篇
药学   30篇
中国医学   2篇
肿瘤学   108篇
  2023年   6篇
  2021年   16篇
  2020年   13篇
  2019年   10篇
  2018年   13篇
  2017年   11篇
  2016年   12篇
  2015年   9篇
  2014年   20篇
  2013年   33篇
  2012年   42篇
  2011年   38篇
  2010年   19篇
  2009年   37篇
  2008年   31篇
  2007年   28篇
  2006年   28篇
  2005年   21篇
  2004年   28篇
  2003年   27篇
  2002年   19篇
  2001年   15篇
  2000年   20篇
  1999年   16篇
  1998年   18篇
  1997年   12篇
  1996年   10篇
  1995年   16篇
  1994年   16篇
  1993年   23篇
  1992年   9篇
  1990年   6篇
  1989年   11篇
  1988年   23篇
  1987年   19篇
  1986年   12篇
  1985年   14篇
  1984年   7篇
  1983年   10篇
  1982年   10篇
  1981年   10篇
  1980年   9篇
  1979年   18篇
  1978年   13篇
  1976年   11篇
  1972年   14篇
  1971年   10篇
  1970年   11篇
  1969年   9篇
  1968年   8篇
排序方式: 共有874条查询结果,搜索用时 31 毫秒
71.
Some evidences suggest that telomere restriction fragment length (TRF-L) is an effective indicator of histopathogenesis in B-cell tumors. As histopathogenesis is relevant for B-cell chronic lymphocytic leukemia (B-CLL) prognosis, TRF-L was assessed by Southern blot in 201 patients and compared to variable immunoglobulin heave chain gene mutational status (VH-MS) and to other known prognostic features. Overall survival (OS), time to first treatment (TTFT) and progression-free survival (PFS) were evaluated. Our results indicate the following: (1) TRF-L is heterogeneous among B-CLL patients (median 6014 bp, range 1465-16 762); (2) TRF-L correlates to VH-MS (r(2)=0.1994, P<0.0001) with VH-mutated patients showing long and VH-unmutated short telomeres; however, 41% of VH-unmutated and 5% of VH-mutated patients did not show this correlation and were thus defined as 'discordant'; (3) TRF-L effectively predicts outcome in terms of TTFT, PFS and OS; (4) VH-unmutated discordant patients have a better clinical outcome than VH-unmutated concordant patients (OS P<0.01, PFS P<0.05) and similar to that of VH-mutated patients (OS, PFS P=NS). Compared to VH-unmutated concordant patients, VH-unmutated discordant patients showed no peculiarity in their immunoglobulin rearrangement nor in their flow cytometry or fluorescence in situ hybridization profile. In conclusion, TRF-L can be helpful to refine prognostication of B-CLL patients, particularly those with a VH-unmutated immunoglobulin sequence.  相似文献   
72.
73.
BACKGROUND: In the present study, the authors consider the possible association between intimal-media thickness of the common carotid arteries and lower limb atherosclerosis, in a group of elderly patients; the authors also consider the presence of cardiovascular risk factors. METHODS: B-mode ultrasound measurement of the intimal-media thickness of the common carotid arteries was performed on 80 subjects. Lower limbs atherosclerosis was defined as the presence of intermittens claudicatio and/or ankle-arm index < 0.9. Baseline clinic examination and blood tests were performed in all subjects to consider the presence of cardiovascular risk factors. Linear regression analysis was used to assess the linear relationship between intimal-media thickness of the common carotid arteries and lower limb atherosclerosis. RESULTS: Linear regression analysis showed a statistical association between increased values of intimal-media thickness of the common carotid arteries and lower limb atherosclerosis. Sixty-four (80%) subjects presented one or more associated cardiovascular risk factors. CONCLUSIONS: The results of the the present study confirm that intimal-media thickness of the common carotid arteries is a marker for the identification of generalized atherosclerosis and may be useful for the identification of subjects, even at early stages, at risk of cardiovascular diseases.  相似文献   
74.
Objectives. To examine the incidence of cancers among persons born in Scotland, Northern Ireland, the Irish Republic, Caribbean Commonwealth and Indian subcontinent and living in England and Wales. Methods. Longitudinal Study of 1% of population of England and Wales followed from 1971 to 1989. Standardised incidence ratios (SIRs) were derived for commonly occurring cancers and all cancers using the age-sex-specific rates for all females and all males in the Longitudinal Study. Results. The incidence of all malignant neoplasms among West Indians (females SIR = 67, male SIR = 70) and Indians (female SIR = 32, male SIR = 52) was low. Among South Asians, this pattern was consistent for Hindus, Sikhs and Moslems. Scottish females showed raised incidence of lung cancer (SIR = 149) and those from the Irish Republic of oral cavity and pharynx (SIR = 321), oesophageal (SIR = 219) and liver (SIR = 373) cancers. Among Northern Irish females, incidence of lung cancer (SIR = 193) was raised. West Indian and South Asian females showed low incidence of breast cancer (SIR = 55 and 45, respectively). High incidence of laryngeal (SIR = 229) and renal (SIR = 203) cancers was observed for Scottish males and of oral cancer (SIR = 259) for males from the Irish Republic. At ages 15-64, raised incidence of prostate cancer (SIR = 129) and of leukaemia (SIR = 252) was also observed for men from the Irish Republic. Northern Irish males showed raised incidence of stomach cancer (SIR = 200). Conclusion. This study describes patterns of cancer incidence among migrant groups, most of which reflect environmental influences. This has challenging implications for sensitive targeting of primary interventions. It is important not to be complacent about lower risks of main cancers among West Indians and South Asians. In all Longitudinal Study members, breast cancer was the most common malignancy among females and lung cancer among males. This was also true for all migrant groups with the exception of Northern Irish women for whom lung cancer was the most common.  相似文献   
75.
76.
Detecting pre-ovulatory luteinizing hormone surges in urine   总被引:2,自引:1,他引:2  
The study objectives were to determine (i) if pre-ovulatory luteinizing hormone (LH) surges, undetected in urine by two immunoradiometric assays (IRMA), were detectable by an ultrasensitive immunofluorometric assay (IFMA) and (ii) the influence of creatinine adjustment on the detection and timing of the urinary LH surges. Daily urine specimens were contributed by healthy 25-36 year old volunteers during 14 ovulatory menstrual cycles for an epidemiological study conducted in 1983-1985. Specimens were selected as having been previously assayed by two IRMA without consistently detecting LH surges. These urine specimens were remeasured using an IFMA and adjusted for creatinine concentration. IFMA measurements revealed unambiguous LH surges in all cycles. Adjusting IRMA urinary LH values for creatinine concentrations revealed previously undetected LH surges in four of eight cycles. Creatinine adjustment also altered the timing of IRMA and IFMA LH surges by 1-5 days. These results demonstrate an IFMA that detects pre- ovulatory LH surges in unpreserved, frozen urine from cycles where such surges were previously undetectable. Further, creatinine adjustment can markedly affect detection and timing of the onset and peak of the urinary LH surge. While our analysis suggests that this adjustment improves the validity of the LH measure, this requires further investigation.   相似文献   
77.
The world's first deliveries of normal babies after use of flow cytometric separated human sperm cells (MicroSort) for preconception gender selection are reported. Offspring were of the desired female gender in 92.9% of the pregnancies. Most of these pregnancies and births were achieved after simple intrauterine insemination.   相似文献   
78.
Summary Selection of populations of Tacaribe virus strain 11573 lethal for mice was carried out by serial intracerebral passage of the virus in adult mice. Viral populations have been characterized by determination of virulence for suckling, weanling, and adult mice, and by histopathologic changes observed in brains of adult mice after intracerebral inoculation. Some of the virus preparations produced 80 to 90 per cent mortality after two or three intracerebral passages in adult mice and maintained this virulence for 1 to 3 passages, after which the virulence rapidly declined with subsequent passages. Clinical signs of infection in adult mice were manifested by a rough hair-coat, ventriflexed posture, diminished activity, increased excitability, flaccid hind-limb extension with progressive paralysis and death. Histologic examination revealed meningoencephalitis.With 2 FiguresIn conducting the research described in this report, the investigators adhered to the Guide for the Care and Use of Laboratory Animals, as promulgated by the Committee on the Revision of the Guide for Laboratory Animal Facilities and Care of the Institute of Laboratory Animal Resources, National Research Council. The facilities are fully accredited by the American Association for Accreditation of Laboratory Animal Care.The views of the authors do not purport to reflect the positions of the Department of the Army or the Department of Defense.  相似文献   
79.
Lung carcinoma remains one of the most frequent and aggressive human neoplasms. Fortunately, in the last decades, the increasing knowledge of the molecular mechanisms leading to cancer development has allowed the use of targeted therapies with improvement of prognosis in many patients. Clinical management has also changed after the introduction of endobronchialultrasonographic bronchoscopy that allows a conservative staging of lung tumors, avoiding the need of mediastinoscopy for lymph node staging. Lung pathologists and cytopathologists are facing the challenge of giving the more comprehensive prognostic and predictive information with ever smaller tissue or cytological samples. The aim of this review is to summarize the molecular testing for non-small cell lung carcinoma and how pathologists can contribute to the patient's outcome with a conscious management of biological samples.  相似文献   
80.
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