全文获取类型
收费全文 | 1195篇 |
免费 | 67篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 17篇 |
妇产科学 | 19篇 |
基础医学 | 148篇 |
口腔科学 | 8篇 |
临床医学 | 98篇 |
内科学 | 230篇 |
皮肤病学 | 7篇 |
神经病学 | 154篇 |
特种医学 | 23篇 |
外国民族医学 | 4篇 |
外科学 | 306篇 |
综合类 | 6篇 |
一般理论 | 1篇 |
预防医学 | 74篇 |
眼科学 | 24篇 |
药学 | 69篇 |
肿瘤学 | 56篇 |
出版年
2023年 | 12篇 |
2022年 | 23篇 |
2021年 | 69篇 |
2020年 | 28篇 |
2019年 | 59篇 |
2018年 | 48篇 |
2017年 | 31篇 |
2016年 | 37篇 |
2015年 | 31篇 |
2014年 | 47篇 |
2013年 | 70篇 |
2012年 | 88篇 |
2011年 | 89篇 |
2010年 | 46篇 |
2009年 | 32篇 |
2008年 | 67篇 |
2007年 | 67篇 |
2006年 | 67篇 |
2005年 | 44篇 |
2004年 | 56篇 |
2003年 | 53篇 |
2002年 | 40篇 |
2001年 | 16篇 |
2000年 | 12篇 |
1999年 | 16篇 |
1998年 | 9篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 7篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1938年 | 1篇 |
排序方式: 共有1265条查询结果,搜索用时 15 毫秒
1.
Double-blind, placebo-controlled comparison of clonazepam and alprazolam for panic disorder 总被引:1,自引:0,他引:1
G E Tesar J F Rosenbaum M H Pollack M W Otto G S Sachs J B Herman L S Cohen S A Spier 《The Journal of clinical psychiatry》1991,52(2):69-76
To test the reported antipanic efficacy of clonazepam, the authors randomized 72 subjects with panic disorder to 6 weeks of treatment with either alprazolam, clonazepam, or placebo. Endpoint analysis demonstrated a significant beneficial effect of both active treatments, but not placebo treatment, on the frequency of panic attacks, overall phobia ratings, and the extent of disability. Comparison of the two active treatments revealed no significant differences and no consistent tendency for one agent to be favored over another, although power to detect small differences was limited. Sedation and ataxia were the most common side effects reported, but these effects were mild and transient and did not interfere with treatment outcome. The results of this double-blind, placebo-controlled trial are consistent with previous reports of clonazepam's antipanic efficacy. 相似文献
2.
Devin V Amin Takeo Kanade Anthony M DiGioia Branislav Jaramaz 《Computer aided surgery》2003,8(1):1-16
OBJECTIVE: To allow non-invasive registration of the bone surface for computer-assisted surgery (CAS), this investigation reports the development and evaluation of intraoperative registration using 2D ultrasound (US) images. This approach employs automatic segmentation of the bone surface reflection from US images tagged with the 3D position to enable the application of CAS to minimally invasive procedures. METHODS: The US-based registration method was evaluated in comparison to point-based registration, which is the predominant method in current clinical use. The absolute accuracy of the US-based registration was determined using a phantom pelvis, with fiducial registration providing the ground truth. The relative accuracy was determined by an intraoperative study comparing the US registration to the point-based registration obtained as part of the HipNav experimental protocol. RESULTS: The phantom pelvis study demonstrated equivalent accuracy between point- and US-based registration under in vitro conditions. In the intraoperative study, the US-based registration was sufficiently consistent with the point-based registration to warrant larger-scale clinical trials of this non-invasive registration method. CONCLUSION: Ultrasound-based registration eliminates the need for physical contact with the bone surface as in point-based registration. As a result, non-invasive registration could fully unlock the potential of computer-assisted surgery, enabling development of the next generation of minimally invasive surgical procedures. 相似文献
3.
Hepatitis A virus (HAV) is distinguished from other picornaviruses by its tropism for the liver in infected hosts, a nonlytic infection in hepatocytes, and a slow and nonlytic growth cycle in cultured cells. Although the genome structure and organization of HAV appear to be similar to those of the other picornaviruses, the viral proteins synthesized in infected cells have not been previously characterized. We have utilized specific antisera raised in rabbits to recombinant HAV proteins expressed in Escherichia coli in an effort to identify both structural and nonstructural proteins in BS-C-1 cells throughout the course of a viral replication cycle. Replication was monitored by dot blot hybridization of viral genomes. Structural proteins VP0, VP1, VP2, and VP3 were found to accumulate during the infection cycle as did viral RNA. Nonstructural proteins 2C and 3D were not detected on immunoblots, although a minor amount of 2C could be detected by immunoprecipitation of lysates of radiolabeled, infected cells. The relative sensitivities of the various antisera were determined, and the failure to observe nonstructural proteins was shown not to be due to decreased sensitivity of the detection reagents. Thus, it appears that HAV nonstructural proteins do not accumulate in infected cells to levels comparable to those of capsid proteins. 相似文献
4.
5.
Embargoes and sanctions are tools of foreign policy. They can induce a decline in economic activity in addition to reducing imports and untoward health effects can supervene, especially among older persons and those with chronic illnesses. Often, violations of the rights of life, health, social services, and protection of human dignity occur among innocent civilians in embargoed nations. This paper examines the effects of embargoes and sanctions against several nations, and calls for studies to determine ways in which economic warfare might be guided by the rule of humanitarian international law, to reduce the effects on civilians. It suggests that the ability to trade in exempted goods and services should be improved, perhaps by establishing uniform criteria and definitions for exemptions, operational criteria under which sanctions committees might function, and methods for monitoring the impact of sanctions on civilian populations in targeted states, particularly with regard to water purity, food availability, and infectious-disease control. Prospective studies are advocated, to generate the data needed to provide better information and monitoring capacity than presently exists. 相似文献
6.
Cytokines and adhesion molecules in renal vasculitis and lupus nephritis 总被引:20,自引:1,他引:19
Tesar V; Masek Z; Rychlik I; Merta M; Bartunkova J; Stejskalova A; Zabka J; Janatkova I; Fucikova T; Dostal C; Becvar R 《Nephrology, dialysis, transplantation》1998,13(7):1662-1667
Background: Plasma levels of some pro-inflammatory
cytokines and soluble adhesion molecules have been suggested to be useful
parameters to assess the activity of antineutrophil cytoplasmic antibody
(ANCA)-positive vasculitis and lupus nephritis. We hypothesized that the
renal activity of these diseases is better reflected by the urinary
excretion and fractional excretion of these molecules.
Methods: Plasma levels and urinary excretion of tumour
necrosis factor-&agr; (TNF-&agr;), interleukin (IL)-6, IL-8, and
the soluble cell adhesion molecules sICAM-1 and sVCAM-1 were measured by
enzyme-linked immunosorbent assay (ELISA) in 15 patients with ANCA-positive
renal vasculitis (eight active, ANCA-A; six in remission, ANCA-R), six
patients with active lupus nephritis (LN), 15 patients with IgA nephropathy
(IgAN) and nine healthy subjects. Fractional excretion of selected
cytokines and adhesion molecules was also calculated.
Results: Patients with ANCA-A had increased urinary
excretion and fractional excretion of TNF-&agr; (9.27±3.19%
vs 0.58±0.02%, P<0.01), IL-6
(120.79±65.83% vs 1.89±0.34%,
P<0.01) and increased fractional excretion of IL-8
(23.34±6.38% vs 2.56±1.07%,
P<0.01) and sVCAM-1 (0.81±0.33% vs
0.03±0.02%, P<0.01) compared with controls. Urinary
excretion of TNF-&agr; and IL-6 and fractional excretion of
TNF-&agr;, IL-6 and IL-8 were higher in ANCA-A than in ANCA-R. Patients
with LN had increased plasma TNF-&agr; (20.52±2.01 pg/ml
vs 12.33±0.23 pg/ml, P<0.05) and
sVCAM-1 (1537.88±276.36 ng/ml vs
692.26±44.42 ng/ml, P<0.05) and increased urinary
excretion of TNF-&agr; (2.81±0.51 &mgr;g/mol creat
vs 0.98±0.05 &mgr;g/mol creat,
P<0.01), IL-8 (35.78±14.03 &mgr;g/mol creat
vs 12.46±5.19 &mgr;g/mol creat,
P<0.05) and sVCAM-1 (48.98±20.20 &mgr;g/mol creat
vs 2.92±1.35 &mgr;g/mol creat,
P<0.01) compared with controls. Patients with IgAN had, in
comparison with controls only increased plasma TNF-&agr;
(18.10±0.57 pg/ml vs 12.33±0.23
pg/ml, P<0.05). Conclusions: Urinary excretion
and fractional excretion, but not plasma levels of selected proinflammatory
cytokines (TNF-&agr;, IL-6 and IL-8) were increased in patients with
active ANCA-positive renal vasculitis, but not in ANCA positive vasculitis
in remission. These parameters may be useful to monitor the activity of
this disease. 相似文献
7.
Large-scale variation among human and great ape genomes determined by array comparative genomic hybridization 总被引:6,自引:1,他引:6
下载免费PDF全文
![点击此处可从《Genome research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Locke DP Segraves R Carbone L Archidiacono N Albertson DG Pinkel D Eichler EE 《Genome research》2003,13(3):347-357
Large-scale genomic rearrangements are a major force of evolutionary change and the ascertainment of such events between the human and great ape genomes is fundamental to a complete understanding of the genetic history and evolution of our species. Here, we present the results of an evolutionary analysis utilizing array comparative genomic hybridization (array CGH), measuring copy-number gains and losses among these species. Using an array of 2460 human bacterial artificial chromosomes (BACs) (12% of the genome), we identified a total of 63 sites of putative DNA copy-number variation between humans and the great apes (chimpanzee, bonobo, gorilla, and orangutan). Detailed molecular characterization of a subset of these sites confirmed rearrangements ranging from 40 to at least 175 kb in size. Surprisingly, the majority of variant sites differentiating great ape and human genomes were found within interstitial euchromatin. These data suggest that such large-scale events are not restricted solely to subtelomeric or pericentromeric regions, but also occur within genic regions. In addition, 5/9 of the verified variant sites localized to areas of intrachromosomal segmental duplication within the human genome. On the basis of the frequency of duplication in humans, this represents a 14-fold positional bias. In contrast to previous cytogenetic and comparative mapping studies, these results indicate extensive local repatterning of hominoid chromosomes in euchromatic regions through a duplication-driven mechanism of genome evolution. 相似文献
8.
Sudan staining of gross specimens with correlated histologic sections was used to localize the accumulation of fat in the aortas of genetically susceptible and resistant strains of pigeons. The birds were maintained on a cholesterol-free grain diet, and studies were done sequentially from ages 1 month to 4 years. Evidence suggests that the accumulation of lipids in musculoelastic cushions located at the origin of small branches is not necessarily a precursor of complicated lesions, but that it occurs concurrently in susceptible and resistant strains. In contrast, in the "lesion area," lipid accumulation is more striking and occurs earlier in the susceptible strain. It precedes proliferation by three to six months. Thus, in this model, two distinct types of fatty streaks can be identified and their biologic features can be defined and related to their propensity for atherogenesis. 相似文献
9.
Summary The phenotypic trait starry colony in Saccharomyces is associated with a high spontaneous rho
–
petite mutability. Genetic analysis of this trait has shown the high rho
– mutability to be caused by several modifying genes present together in the strains studied. Every single modifying gene produces only a relatively small enhancement of the rho
– mutability. 相似文献
10.
David K. C. Cooper Hidetaka Hara Hayato Iwase Takayuki Yamamoto Zheng‐Yu Wang Abhijit Jagdale Mohamed H. Bikhet Huy Q. Nguyen Jeremy B. Foote Wayne D. Paris David Ayares Vineeta Kumar Douglas J. Anderson Jayme E. Locke Devin E. Eckhoff 《Clinical transplantation》2021,35(1):e14139
Pig organ xenotransplantation offers a solution to the shortage of deceased human organs for transplantation. The pathobiological response to a pig xenograft is complex, involving antibody, complement, coagulation, inflammatory, and cellular responses. To overcome these barriers, genetic manipulation of the organ‐source pigs has largely been directed to two major aims—(a) deletion of expression of the known carbohydrate xenoantigens against which humans have natural (preformed) antibodies, and (b) transgenic expression of human protective proteins, for example, complement‐ and coagulation‐regulatory proteins. Conventional (FDA‐approved) immunosuppressive therapy is unsuccessful in preventing an adaptive immune response to pig cells, but blockade of the CD40:CD154 costimulation pathway is successful. Survival of genetically engineered pig kidneys in immunosuppressed nonhuman primates can now be measured in months. Non‐immunological aspects, for example, pig renal function, a hypovolemia syndrome, and rapid growth of the pig kidney after transplantation, are briefly discussed. We suggest that patients on the wait‐list for a deceased human kidney graft who are unlikely to receive one due to long waiting times are those for whom kidney xenotransplantation might first be considered. The potential risk of infection, public attitudes to xenotransplantation, and ethical, regulatory, and financial aspects are briefly addressed. 相似文献