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   31808篇
  免费   1801篇
  国内免费   99篇
耳鼻咽喉   251篇
儿科学   1095篇
妇产科学   915篇
基础医学   3573篇
口腔科学   392篇
临床医学   5826篇
内科学   5303篇
皮肤病学   351篇
神经病学   3139篇
特种医学   599篇
外国民族医学   2篇
外科学   3013篇
综合类   295篇
现状与发展   1篇
一般理论   50篇
预防医学   4454篇
眼科学   445篇
药学   1847篇
中国医学   33篇
肿瘤学   2124篇
  2023年   192篇
  2022年   325篇
  2021年   586篇
  2020年   420篇
  2019年   649篇
  2018年   803篇
  2017年   559篇
  2016年   633篇
  2015年   670篇
  2014年   985篇
  2013年   1590篇
  2012年   2288篇
  2011年   2422篇
  2010年   1284篇
  2009年   1131篇
  2008年   2186篇
  2007年   2379篇
  2006年   2269篇
  2005年   2201篇
  2004年   2027篇
  2003年   1953篇
  2002年   1867篇
  2001年   219篇
  2000年   183篇
  1999年   278篇
  1998年   371篇
  1997年   310篇
  1996年   245篇
  1995年   274篇
  1994年   213篇
  1993年   210篇
  1992年   134篇
  1991年   136篇
  1990年   136篇
  1989年   113篇
  1988年   104篇
  1987年   95篇
  1986年   93篇
  1985年   103篇
  1984年   124篇
  1983年   126篇
  1982年   144篇
  1981年   139篇
  1980年   118篇
  1979年   56篇
  1978年   71篇
  1977年   61篇
  1976年   48篇
  1975年   36篇
  1974年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
PURPOSE: Malignant B lineage cells in Waldenstrom's macroglobulinemia (WM) express a unique clonotypic IgM VDJ. The occurrence of biclonal B cells and their clonal relationships were characterized. EXPERIMENTAL DESIGN: Bone marrow and blood from 20 WM patients were analyzed for clonotypic VDJ sequences, clonal B-cell frequencies, and the complementary determining region 3 profile. RESULTS: Two different clonotypic VDJ sequences were identified in 4 of 20 WM. In two cases, partner clones had different VDJ rearrangements, with one clonotypic signature in bone marrow and a second in blood. For both cases, the bone marrow clone was hypermutated, whereas the blood clone was germ line or minimally mutated. In two other cases, partner clones shared a common VDJ rearrangement but had different patterns of somatic mutations. They lacked intraclonal diversity and were more abundant in bone marrow than in blood. VDJ mutation profiles suggested they arose from a common IgM progenitor. Single-cell analysis in one case indicated the partner clones were reciprocally expressed, following rules of allelic exclusion. CONCLUSIONS: The existence of two B-cell clones having distinct VDJ sequences is common in WM, suggesting that frequent transformation events may occur. In two cases, the partner clones had distinct tissue distributions in either blood or bone marrow, were of different immunoglobulin isotypes, and in one case exhibited differential response to therapy. The contributions of each clone are unknown. Their presence suggests that WM may involve a background of molecular and cellular events leading to emergence of one or more malignant clones.  相似文献   
132.
The purpose of this study is to describe the characteristic computed tomographic (CT) signs of small bowel perforation after blunt abdominal trauma and to evaluate their sensitivity. Nineteen preoperative CT scans were obtained from 16 patients with surgically proven small bowel rupture secondary to blunt abdominal trauma. Only the CT findings described in the original CT reports were used. Eleven of 19 CT scans (58 %) had findings that were unequivocal for bowel rupture (i.e., extraluminal air and/or extravasation of oral contrast medium). Seven CT scans (37 %) had findings that were suggestive of severe small bowel injury (i.e., focal small bowel wall thickening and/or free peritoneal fluid without other accompanying organ injuries). In all, 95 % of cases of small bowel rupture had either pathognomonic or suggestive CT findings. One CT scan did not demonstrate small bowel wall thickening, although a hemoperitoneum was present. CT is a sensitive method for suggesting severe small bowel injury and rupture secondary to blunt abdominal trauma.  相似文献   
133.
134.
Renal transplantation has increased the longevity of patients with uremia. An increasing number undergo aortic reconstruction, which exposes the transplanted kidney to ischemic injury. To evaluate the risk for renal failure, loss of the transplant, and methods of renal protection, we reviewed our experience. Clinical data were reviewed for 10 consecutive patients (7 men, 3 women; mean age 52.7 years [range 32 to 75 years]) with a transplanted kidney who underwent aortic reconstruction between 1977 and 1994 at our institution. Mean interval between renal transplantation and aortic reconstruction was 5.9 years (range 1 month to 12.7 years). Seven patients required emergency repair because of dissection (2 patients), aneurysm rupture (4 patients), or symptomatic aneurysm (1 patient); three underwent elective repair. Reasons for reconstruction included aortic dissection (2 patients), aneurysm of the descending thoracic (2 patients), thoracoabdominal (1 patient), or abdominal aorta (3 patients), and aortoiliac occlusive disease (2 patients). Patients with thoracic or thoracoabdominal reconstructions underwent repair with atriofemoral, aortofemoral, or femorofemoral shunt placement or bypass. Of the five abdominal aortic reconstructions, the kidney was protected with aortofemoral shunt placement in one patient and cold renal perfusion in three. In two of them, topical cooling of the kidney also was used. One patient with acute aortic dissection died at 39 days as a result of respiratory failure. Loss of the recently transplanted kidney was caused by acute rejection. One patient had a transient increase in serum creatinine concentration. Eight had no worsening of renal function, and none of the nine survivors lost the transplanted kidney. We conclude that aortic reconstruction can be safely performed in kidney transplant recipients. Patients in whom thoracic or thoracoabdominal aortic reconstruction was required were protected with an atriofemoral or aortofemoral bypass or shunt. Patients undergoing abdominal aortic reconstruction did well when cold renal perfusion with or without local cooling of the transplant was used for renal protection. Transplanted kidneys appeared to tolerate ischemic injury similarly to native kidneys.Presented at the Twentieth Annual Meeting of the Peripheral Vascular Surgery Society, New Orleans, La., June 10, 1995.  相似文献   
135.
Summary: Purpose: We wished to determine the effect of renal impairment on the pharmacokinetics and tolerability of the new antiepileptic drug tiagabine (TGB).
Methods: We assessed TGB pharmacokinetics and tolerability in 25 subjects with various degrees of renal function (based on creatinine clearance, n = 4–6 per group) from healthy (group I) to requiring hemodialysis (group V) in a single and multiple dose (every 12h), one-period (groups I-IV) or a single dose, two-period (group V) study (4-mg oral doses of TGB · HCl). Blood samples were collected after the first dose (both periods for group V) and after the last dose on day 5 (groups I-IV). TGB plasma concentrations and plasma protein binding were determined by high-performance liquid chromatography (HPLC) and ultrafiltration, respectively.
Results: TGB was well tolerated by all study subjects. The pharmacokinetics of TGB were similar in all subjects; no pharmacokinetic parameter (based on either total or unbound concentrations) was statistically correlated with creatinine clearance. For total TGB in plasma, single-dose mean values of the maximum plasma concentration, clearance, and half-life (t1/2) ranged from 52 to 108 ng/ml, from 7.14 to 11.02 I/h, and from 6.4 to 8.4 h, respectively.
Conclusions: TGB pharmacokinetics and tolerability were independent of renal function; therefore, dosage adjustment is unnecessary for epilepsy patients with renal impairment.  相似文献   
136.
The purpose of this study was to examine the correlates of post-shelter maternal family satisfaction in a group of youth who were reunified with their families following a shelter stay. Findings indicated that higher ratings of family satisfaction were related to greater maternal problem solving skill and less family conflict.  相似文献   
137.
Pharmaceutical care is a concept outlining the responsibilities of individual pharmacists to individual patients. Although widely accepted on a philosophical basis, there is a lack of comprehensive information about the functions and responsibilities pharmacists undertake when providing pharmaceutical care. Pharmacy educators and practitioners at the faculty of pharmacy, University of Toronto, developed and informally tested a process that details the practice functions required of pharmacists when providing pharmaceutical care as originally defined.  相似文献   
138.
The objective of this study has been to define the role of polysensory association cortex in the generation of "wave NA" and of "wave C," long-latency auditory-evoked potentials recorded from the vertex of conscious cats as, respectively, a marked negative potential of latency 30-48 msec followed by a broad positive wave of latency 50-75 msec. Wave C may represent the feline analogue of the longer latency human auditory-evoked potential wave P2, insofar as both waveforms are very large amplitude, long duration positivities characterized by long recovery cycles. Based on previous studies of wave C and the generators of other middle-latency evoked potentials, we hypothesized that both wave NA and wave C might reflect, at least in part, the cortical culmination of a nonlemniscal line auditory association system arising in reticulothalamic projections to intralaminar and associated ventral thalamic regions. Relays from these thalamic areas are known to project to polysensory association cortex, including pericruciate gyrus, anterolateral gyrus, and medial suprasylvian gyrus. Therefore we implemented a series of lesion experiments to characterize the role of each of these cortical areas in the production of wave NA and wave C. Our results indicate that all three polysensory association areas contribute significantly to both waves NA and C, although the largest effects followed ablation of the pericruciate area alone. Thus, the generator substrates of waves NA and C appear to involve a long-recovery cycle system which functionally incorporates activation of association cortex.  相似文献   
139.
Although there is relatively little information concerning the oral health of handicapped adults there is increasing evidence to suggest that their oral condition, particularly periodontal health, is poor. The present investigation involved assessment of 382 handicapped patients attending four different Adult Training Centres in Birmingham. The caries status, oral hygiene, and periodontal conditions were evaluated and the Community Periodontal Index of Treatment Need (CPITN) was calculated. In order to assess the manual dexterity and the comprehension of the trainees a standard test was devised. This consisted of timing each participant in carrying out simple instructions to pick up and position certain common objects. The results indicated high levels of plaque, calculus, and bleeding with a mean CPITN of 7.43. The mean time taken for the manual dexterity and comprehension test was 23.9 seconds with a range from 10 to 80 seconds, S.E.+/- 1.33. This compares with results from 34 "normal" adults of a mean time of 8.2 seconds +/- 1.8 with a range of 6 to 12 seconds. There was no significant correlation between the Manual Dexterity and Comprehension scores and the periodontal indices in the handicapped adults.  相似文献   
140.
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