全文获取类型
收费全文 | 1431篇 |
免费 | 116篇 |
国内免费 | 30篇 |
专业分类
儿科学 | 67篇 |
妇产科学 | 52篇 |
基础医学 | 160篇 |
口腔科学 | 56篇 |
临床医学 | 167篇 |
内科学 | 282篇 |
皮肤病学 | 21篇 |
神经病学 | 76篇 |
特种医学 | 270篇 |
外科学 | 177篇 |
综合类 | 21篇 |
预防医学 | 53篇 |
眼科学 | 8篇 |
药学 | 116篇 |
中国医学 | 1篇 |
肿瘤学 | 50篇 |
出版年
2022年 | 11篇 |
2021年 | 17篇 |
2019年 | 8篇 |
2018年 | 28篇 |
2017年 | 19篇 |
2016年 | 22篇 |
2015年 | 26篇 |
2014年 | 35篇 |
2013年 | 34篇 |
2012年 | 38篇 |
2011年 | 45篇 |
2010年 | 52篇 |
2009年 | 40篇 |
2008年 | 39篇 |
2007年 | 51篇 |
2006年 | 44篇 |
2005年 | 41篇 |
2004年 | 47篇 |
2003年 | 39篇 |
2002年 | 31篇 |
2001年 | 25篇 |
2000年 | 22篇 |
1999年 | 37篇 |
1998年 | 66篇 |
1997年 | 76篇 |
1996年 | 79篇 |
1995年 | 50篇 |
1994年 | 43篇 |
1993年 | 44篇 |
1992年 | 27篇 |
1991年 | 22篇 |
1990年 | 22篇 |
1989年 | 49篇 |
1988年 | 44篇 |
1987年 | 35篇 |
1986年 | 38篇 |
1985年 | 36篇 |
1984年 | 13篇 |
1983年 | 14篇 |
1982年 | 16篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1977年 | 15篇 |
1976年 | 11篇 |
1975年 | 11篇 |
1972年 | 9篇 |
1970年 | 7篇 |
1966年 | 7篇 |
排序方式: 共有1577条查询结果,搜索用时 15 毫秒
1.
Peter Chiba Barbara Tell Walter Jger Elisabeth Richter Manuela Hitzlera Gerhard Ecker 《Archiv der Pharmazie》1997,330(11):343-347
A series of 5-hydroxy and 5-benzyloxy analogs of the antiarrhythmic and multidrug resistance (MDR) modulating drug propafenone was synthesized and the MDR-modulating activity of the compounds was evaluated using a daunomycin efflux assay system. The key step of the synthesis is the selective reduction of the double bond in 1 without cleavage of the benzyl group thus leading to the phenol 3 . Alkylation with epichlorohydrine followed by nucleophilic epoxide ring opening gave the benzylated target compounds 5a–d . Subsequent cleavage of the benzyl group gave the 5-hydroxy analogs 6a–d . Structure activity relationship studies showed, that the 5-hydroxy derivates 6a–d fit the log P/log potency correlation line previously established for a series of propafenone analogs. In contrast, all four 5-benzyloxy analogs 5a–d showed almost identical EC50 values, independent of their log P value. 相似文献
2.
Hirschsprung's disease: associated abnormalities and demography. 总被引:3,自引:0,他引:3
We here examine the demographic parameters of patients with Hirschsprung's disease. The study population includes all patients with histologically confirmed disease treated at the Children's Hospital Medical Center of Boston over the 25-year period extending from 1961 through the first quarter of 1986. There were 179 cases. Overall, children with Hirschsprung's disease were found less likely to be first born (P less than .01). This relationship was seen to persist irrespective of maternal age, maternal race, or type of disease. The implications of this finding are discussed. Overall, 22% of these children had one or more associated abnormalities involving the neurological, cardiovascular, urological, and gastrointestinal systems. Many of the disorders appeared to be related to neurocrestopathies. Frequent associations included Down's syndrome, defects in cardiac septation, tetralogy of Fallot, and Dandy-Walker syndrome. These conditions occurred more frequently than would have been predicted through chance alone. This study found no association between an increased maternal age and the occurrence of Hirschsprung's disease. This study also found that approximately 7% of the affected children had been born prematurely. 相似文献
3.
In a prospective, randomized study of insemination with donor semen,
intracervical insemination by straw was compared with insemination using a
cervical cap with an intracervical reservoir. A total of 91 patients
completed 486 treatment cycles. There were no significant differences in
age, parity, indication for insemination by donor, or method of cycle
monitoring between women who became pregnant and those who did not conceive
with either insemination method. In 236 standard intracervical insemination
cycles, 14 patients became pregnant (5.9% per cycle), whereas 38 patients
conceived in 250 cervical cap cycles (15.2% per cycle). Both the crude
pregnancy rates and the cumulative pregnancy rates calculated by the
Kaplan-Meier life-table method were significantly different (chi(2)-test, P
< 0.001, and log-rank test, P < 0.005 respectively). Pregnancy rates
in artificial insemination with cryopreserved donor semen may be improved
by the use of a cervical cap when compared to cervical insemination by
straw. The use of the cervical cap may prolong the exposure of the
spermatozoa to the cervical mucus and prevent the backflow of semen into
the vagina.
相似文献
4.
Stress fracture as a cause of chronic pain following revision total hip arthroplasty. Report of two cases 总被引:1,自引:0,他引:1
Femoral stress fractures following revision total hip arthroplasty developed about a cortical window in two patients. These cases differ from previously reported fractures in that there was no significant trauma, the pain was gradual in onset, and there was no displacement at the fracture site. Tomograms and radionuclide bone scans were necessary to reveal the fracture. One femur healed with hip spica immobilization, while the other required bone grafting. Femoral stress fractures should be considered in the differential diagnosis of patients with thigh pain after revision total hip arthroplasty, particularly if a cortical window had been necessary. 相似文献
5.
6.
7.
8.
A 50-kDa membrane protein mediates sialic acid-independent binding and infection of conjunctival cells by adenovirus type 37 总被引:6,自引:0,他引:6
The ocular tropism of adenovirus type 37 (Ad37) does not correlate with the wide distribution of the 46-kDa coxsackievirus and adenovirus receptor (CAR), the major receptor for most adenovirus serotypes. We previously found that Ad37 infects and binds well to conjunctival cells (Chang C), but poorly to lung epithelial (A549) cells that express CAR and hypothesized that this serotype uses a distinct receptor that is selectively expressed on conjunctival cells. To test this, we produced particles of a fiber-deleted Ad5 vector containing the Ad37 fiber protein. The "pseudotyped" vector infected Chang C cells better than A549 cells using a CAR-independent pathway. Ad37 binding was calcium-dependent and was abolished by protease digestion of cell surface proteins. Using a virus overlay protein blot assay (VOPBA), we detected calcium-dependent Ad37 binding to 50- and 60-kDa membrane proteins on permissive Chang C cells. In contrast, calcium-dependent binding was detected with only the 60-kDa protein on nonpermissive A549 cells. Ad19p, a closely related serotype that failed to bind to conjunctival cells, recognized the 60-kDa, but not the 50-kDa, protein. Ad37 has been reported to use sialic acid instead of CAR as a cell receptor on A549 cells. Pretreatment of Chang C cells with neuraminidase abolished Ad37 binding to only the 60-kDa protein, suggesting that sialic acid mediates Ad37 binding to the 60-kDa protein. The pseudotyped Ad37 vector was also able to infect neuraminidase-treated Chang C cells. Thus, subgroup D adenoviral binding to the 50-kDa protein is calcium-dependent and cell type- and serotype-specific, whereas binding to the 60-kDa protein is not necessary for infection of conjunctival cells. Together, these data suggest that the 50-kDa protein is the major receptor for Ad37 on conjunctival cells. 相似文献
9.
Mahadevaiah SK; Odorisio T; Elliott DJ; Rattigan A; Szot M; Laval SH; Washburn LL; McCarrey JR; Cattanach BM; Lovell-Badge R; Burgoyne PS 《Human molecular genetics》1998,7(4):715-727
An RNA-binding motif (RBM) gene family has been identified on the human Y
chromosome that maps to the same deletion interval as the 'azoospermia
factor' (AZF). We have identified the homologous gene family (Rbm) on the
mouse Y with a view to investigating the proposal that this gene family
plays a role in spermatogenesis. At least 25 and probably >50 copies of
Rbm are present on the mouse Y chromosome short arm located between Sry and
the centromere. As in the human, a role in spermatogenesis is indicated by
a germ cell-specific pattern of expression in the testis, but there are
distinct differences in the pattern of expression between the two species.
Mice carrying the deletion Yd1, that maps to the proximal Y short arm, are
female due to a position effect resulting in non-expression of Sry ;
sex-reversing such mice with an Sry transgene produces males with a high
incidence of abnormal sperm, making this the third deletion interval on the
mouse Y that affects some aspect of spermatogenesis. Most of the copies of
Rbm map to this deletion interval, and the Yd1males have markedly reduced
Rbm expression, suggesting that RBM deficiency may be responsible for, or
contribute to, the abnormal sperm development. In man, deletion of the
functional copies of RBM is associated with meiotic arrest rather than
sperm anomalies; however, the different effects of deletion are consistent
with the differences in expression between the two species.
相似文献
10.
MA Ebert J Blight S Price A Haworth C Hamilton D Cornes DJ Joseph 《Journal of Medical Imaging and Radiation Oncology》2004,48(3):347-352
Digital data from 3‐D treatment planning computers is generally used for patient planning and then never considered again. However, such data contains enormous quantities of information regarding patient geometries, tissue outlining, treatment approaches and dose distributions. Were such data accessible from planning systems from multiple manufacturers, there would be substantial opportunities for undertaking quality assurance of radiotherapy clinical trials, prospective assessment of trial outcomes and basic treatment planning research and development. The technicalities of data exchange between planning systems are outlined, and previous attempts at producing systems capable of viewing and/or manipulating imaging and radiotherapy digital data reviewed. Development of a software system for enhancing the quality of Australasian clinical trials is proposed. 相似文献