全文获取类型
收费全文 | 2077篇 |
免费 | 135篇 |
国内免费 | 45篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 95篇 |
妇产科学 | 26篇 |
基础医学 | 144篇 |
口腔科学 | 42篇 |
临床医学 | 286篇 |
内科学 | 343篇 |
皮肤病学 | 44篇 |
神经病学 | 61篇 |
特种医学 | 293篇 |
外科学 | 294篇 |
综合类 | 205篇 |
预防医学 | 141篇 |
眼科学 | 16篇 |
药学 | 128篇 |
2篇 | |
中国医学 | 34篇 |
肿瘤学 | 87篇 |
出版年
2022年 | 31篇 |
2021年 | 33篇 |
2020年 | 30篇 |
2018年 | 23篇 |
2017年 | 23篇 |
2016年 | 18篇 |
2015年 | 33篇 |
2014年 | 48篇 |
2013年 | 76篇 |
2012年 | 82篇 |
2011年 | 86篇 |
2010年 | 90篇 |
2009年 | 106篇 |
2008年 | 67篇 |
2007年 | 81篇 |
2006年 | 82篇 |
2005年 | 54篇 |
2004年 | 49篇 |
2003年 | 49篇 |
2002年 | 46篇 |
2001年 | 36篇 |
2000年 | 27篇 |
1999年 | 30篇 |
1998年 | 82篇 |
1997年 | 74篇 |
1996年 | 72篇 |
1995年 | 67篇 |
1994年 | 41篇 |
1993年 | 51篇 |
1992年 | 15篇 |
1991年 | 21篇 |
1990年 | 16篇 |
1989年 | 32篇 |
1988年 | 45篇 |
1987年 | 42篇 |
1986年 | 31篇 |
1985年 | 33篇 |
1984年 | 21篇 |
1983年 | 26篇 |
1982年 | 17篇 |
1980年 | 16篇 |
1977年 | 15篇 |
1963年 | 17篇 |
1960年 | 14篇 |
1959年 | 22篇 |
1958年 | 29篇 |
1957年 | 19篇 |
1956年 | 30篇 |
1955年 | 42篇 |
1954年 | 35篇 |
排序方式: 共有2257条查询结果,搜索用时 0 毫秒
21.
22.
23.
24.
25.
26.
Horne G; Jamaludin A; Critchlow JD; Falconer DA; Newman MC; Oghoetuoma J; Pease EH; Lieberman BA 《Human reproduction (Oxford, England)》1998,13(11):3045-3048
Insemination with donor spermatozoa is an integral part of infertility
treatment. For the last 3 years in our unit, intrauterine insemination with
donor spermatozoa (IUID) has been used in preference to vaginal
insemination. In this retrospective study, patients were offered an initial
course of five single intrauterine inseminations with cryopreserved donor
spermatozoa and treatment was then reviewed. A total of 389 patients
received 1465 inseminations. In all, 1119 cycles were monitored using
luteinizing hormone serum analyses and 346 cycles using the urine home test
kits. The clinical pregnancy rate per insemination for the cycles monitored
by the serum assay was 18.0% (202/1119) compared with the urine cycles
(13.7%, 46/346) (P <05). The pregnancy loss rate was not significantly
different (14.4%, 29/202 and 21.7%, 10/46) (serum and urine cycles
respectively). The viable clinical pregnancy rate was significantly higher
(P <03) for the serum cycles than for the cycles using the urinary
monitoring (15.5%, 173/1119 and 10.4%, 36/346 respectively). The cycles
monitored by serum assay had a significantly higher cumulative viable
clinical pregnancy rate (P <0001) of 70.2% after nine inseminations
compared with the urine monitored cycles of 54.8%. The majority of patients
opted for the serum cycles, with a minority self-selecting the urine cycles
mainly for travelling convenience. The explanation for the significant
differences between the viable clinical pregnancy rates per insemination
and the cumulative viable clinical pregnancy rates may be due to the
sensitivity of the urine home test kit or the patients' interpretation of
the result.
相似文献
27.
28.
B lymphocytes secreting IgG linked to latent transforming growth factor- beta prevent primary cytolytic T lymphocyte responses 总被引:3,自引:0,他引:3
B lymphocytes secreting IgG linked to latent transforming growth factor
(TGF)-beta (IgG-TGF-beta) prevent cytolytic T lymphocyte (CTL) responses to
unrelated antigens in mixed lymphocyte cultures (MLC) so long as resting
resident macrophages and functional Fc receptors are present. This was
shown using IgG-secreting plaque-forming cells (PFC) to sheep erythrocytes
(SRBC) obtained from popliteal lymph nodes of mice injected repeatedly in
foot pads with SRBC. Remarkably, as few as approximately 300 PFC prevented
CTL responses of 5 x 10(5) normal syngeneic spleen cells in MLC.
Supranatants of short-term cultures of PFC also prevented CTL responses,
and suppression was prevented by eliminating or dissociating IgG and
TGF-beta present in supranatants or by antibody against active TGF-beta.
Furthermore, the latency- associated peptide of latent TGF-beta was
detected in approximately 10% of foci of IgG captured from single PFC,
indicating that at least some B lymphocytes secrete IgG-TGF-beta as a
complex. Resting resident macrophages (which do not produce latent
TGF-beta) and functional Fc receptors were required for suppression,
consistent with idea that IgG- TGF-beta is taken up through Fc receptors
for IgG and that active TGF- beta, cleaved from latent TGF-beta of the
complex, is delivered directly to potentially responding CTL. If CTL
responses in man are similarly regulated by B lymphocytes, then an ongoing
B cell response in patients with chronic viral infections or bearing
immunogenic cancers may prevent effective therapeutic vaccination.
相似文献
29.
30.
Kucharczyk W; Brant-Zawadzki M; Lemme-Plaghos L; Uske A; Kjos B; Feinberg DA; Norman D 《Radiology》1985,157(1):95-101
In multiple spin-echo image sequences of blood flow, the "even-echo" phenomenon produces an absolute increase in signal magnitude from first- to second-echo images of normal vessels harboring slow flow. Distinguishing this from the apparent relatively high signal intensity seen on second-echo images in pathologic foci of stationary tissue is important to the diagnostician. Selected case material containing two tissue types was reviewed retrospectively: tissues known to harbor slow flow, such as normal veins and venous sinuses and vascular malformations, and tissues that have long transverse (T2) relaxation times and appear as intense structures on second-echo images, such as neoplasms, infarcts, and regions of demyelination. Calculations of T2 parameters were made by computer for defined regions of interest. T2 images were also generated. Visual inspection of the acquired images did not reliably distinguish increased intensity due to even-echo rephasing from the relative changes between adjacent tissues seen on second-echo images. More definitive differentiation of the even-echo phenomenon was provided by calculated values of T2 and computer-synthesized T2 images representing acquired intensity data of two-echo sequences. The synthesized images were especially useful when stationary tissue with lengthened T2 values was adjacent to or in proximity to vessels or vascular lesions. A five spin-echo image sequence was valuable for separating slow flow from stationary tissue by a technique of synthesizing T2-difference images using three consecutive echoes. 相似文献