全文获取类型
收费全文 | 792篇 |
免费 | 45篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 25篇 |
妇产科学 | 13篇 |
基础医学 | 161篇 |
口腔科学 | 9篇 |
临床医学 | 104篇 |
内科学 | 136篇 |
皮肤病学 | 15篇 |
神经病学 | 31篇 |
特种医学 | 57篇 |
外科学 | 140篇 |
综合类 | 18篇 |
一般理论 | 1篇 |
预防医学 | 30篇 |
眼科学 | 25篇 |
药学 | 84篇 |
肿瘤学 | 33篇 |
出版年
2021年 | 9篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 13篇 |
2013年 | 26篇 |
2012年 | 33篇 |
2011年 | 19篇 |
2010年 | 28篇 |
2009年 | 20篇 |
2008年 | 27篇 |
2007年 | 52篇 |
2006年 | 35篇 |
2005年 | 30篇 |
2004年 | 19篇 |
2003年 | 18篇 |
2002年 | 19篇 |
2001年 | 28篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 16篇 |
1997年 | 24篇 |
1996年 | 8篇 |
1995年 | 18篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 23篇 |
1991年 | 17篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1976年 | 6篇 |
1975年 | 10篇 |
1968年 | 10篇 |
1943年 | 8篇 |
1941年 | 5篇 |
1940年 | 5篇 |
1939年 | 6篇 |
1938年 | 8篇 |
1928年 | 7篇 |
1927年 | 5篇 |
1926年 | 6篇 |
1925年 | 6篇 |
排序方式: 共有885条查询结果,搜索用时 15 毫秒
1.
2.
We describe a case, unique to the best of our knowledge, in which bigeminal supraventricular premature contractions were detected in a normal newborn. These arrhythmias disappeared spontaneously after the twelfth day of life. Since they do not appear to evolve towards paroxysmal supraventricular tachycardia, treatment with antiarrhythmic drugs is not recommended. 相似文献
3.
C. H. Mensing V. Schleusner T. Matthes C. A. Sander 《Der Hautarzt; Zeitschrift für Dermatologie, Venerologie, und verwandte Gebiete》2006,57(6):532-536
Ohne Zusammenfassung 相似文献
4.
Low molecular weight heparin and prevention of postoperative thrombosis in abdominal surgery. 总被引:3,自引:0,他引:3
K Koppenhagen J Adolf M Matthes E Tr?ster J D Roder S Hass H M Fritsche H Wolf 《Thrombosis and haemostasis》1992,67(6):627-630
In a prospective, double-blind, randomized multicenter trial the efficacy and safety of low molecular weight heparin and unfractionated heparin were compared for the prevention of postoperative deep vein thrombosis in patients undergoing abdominal surgery. Six hundred and seventy-three patients were randomly allocated to the two prophylaxis groups; 20 of these, however, did not undergo surgery and did not receive any prophylaxis. Of the remaining 653 patients 323 received one subcutaneous injection of 3,000 anti-Xa units of low molecular weight heparin and 330 received subcutaneously 5,000 U heparin three times a day. Treatment was initiated 2 h preoperatively and continued for 7 to 10 days. The occurrence of DVT was determined by the 125I-labelled fibrinogen uptake test and phlebography. Venous thrombosis was diagnosed in 24 of 323 patients (7.4%) treated with low molecular weight heparin and in 26 of 330 patients (7.9%) treated with low-dose heparin. DVT of proximal veins was detected in four patients of the low molecular weight heparin group and in three patients of the low-dose heparin group. During the observation period three pulmonary emboli - one fatal and two non-fatal - occurred in patients receiving prophylaxis with low-dose heparin. No pulmonary embolism was found in patients treated with low molecular weight heparin. Both prophylactic schemes were well tolerated. Intra- and postoperative blood loss, incidence of wound hematoma, frequency and volume of intra- and postoperative blood transfusion were similar in both groups with a slight advantage for the low molecular weight heparin group.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
5.
Calcium ionophore-induced acrosome reaction correlates with fertilization rates in vitro in patients with teratozoospermic semen 总被引:5,自引:3,他引:5
The aim of this study was to determine the relationship between calcium
ionophore A23187-induced acrosome reaction (AR) and sperm fertilizing
ability. Semen samples remaining after preparation for standard IVF were
studied in 109 patients who had sperm concentrations > or =20 x
10(6)/ml. Ionophore-induced AR was performed on motile spermatozoa selected
by centrifugation on a Percoll gradient. Semen analysis was performed using
standard methods. Patients with higher (>50%, n = 76) fertilization
rates had significantly higher ionophore-induced AR than patients with
lower (<50%, n = 33) fertilization rates (49 +/- 14 versus 38 +/- 21%, P
< 0.05). When the data from all patients were analysed by logistic
regression, only the percentage sperm motility in insemination medium and
ionophore-induced AR were significantly related to fertilization rates.
Similar results were also obtained when the data from a subgroup of
patients with poor (<15% normal) sperm morphology were analysed.
However, when patients with normal sperm morphology > or =15% were
analysed separately, only sperm count and the percentage of spermatozoa
with progressive motility in semen were significantly related to
fertilization rates. In conclusion, ionophore- induced AR was significantly
related to fertilization rates in vitro mainly in patients with
teratozoospermic semen. Tests for ionophore- induced AR may provide
additional information about sperm fertilizing ability but may not indicate
specific defects of the physiological AR.
相似文献
6.
7.
Detection of reactive oxygen species (ROS) and apoptosis in human fragmented embryos 总被引:8,自引:2,他引:8
Yang HW; Hwang KJ; Kwon HC; Kim HS; Choi KW; Oh KS 《Human reproduction (Oxford, England)》1998,13(4):998-1002
In human in-vitro fertilization (IVF)-embryo transfer, the in-vitro culture
environment differs from in-vivo conditions in that the oxygen
concentration is higher, and in such conditions the mouse embryos show a
higher concentration of reactive oxygen species (ROS) in simple culture
media. ROS are believed to cause damage to cell membranes and DNA
fragmentation in somatic cells. This study was conducted to ascertain the
level of H2O2 concentration within embryos and the morphological features
of cell damage induced by H2O2. A total of 62 human oocytes and embryos (31
fragmented, 15 non-fragmented embryos, 16 unfertilized oocytes) was
obtained from the IVF-embryo transfer programme. The relative intensity of
H2O2 concentrations within embryos was measured using
2',7'-dichlorodihydrofluorescein diacetate by Quanti cell 500 fluorescence
imaging and DNA fragmentation was observed with transmission electron
microscopy and an in-situ apoptosis detection kit. The H2O2 concentrations
were significantly higher in fragmented embryos (72.21 +/- 9.62, mean +/-
SEM) compared to non-fragmented embryos (31.30 +/- 3.50, P < 0.05) and
unfertilized oocytes (30.75 +/- 2.67, P < 0.05). Apoptosis was observed
only in fragmented embryos, and was absent in non-fragmented embryos.
Electron microscopic findings confirmed apoptotic bodies and cytoplasmic
condensation in the fragmented blastomeres. We conclude that there is a
direct relationship between increased H2O2 concentration and apoptosis, and
that further studies should be undertaken to confirm these findings.
相似文献
8.
Stein TP; Oram-Smith JC; Leskiw MJ; Wallace HW; Long LC; Leonard JM 《The American journal of physiology》1976,230(5):1321-1325
9.
Interchromosomal duplications of the adrenoleukodystrophy locus: a phenomenon of pericentromeric plasticity 总被引:13,自引:5,他引:13
Eichler EE; Budarf ML; Rocchi M; Deaven LL; Doggett NA; Baldini A; Nelson DL; Mohrenweiser HW 《Human molecular genetics》1997,6(7):991-1002
A 9.7 kb segment encompassing exons 7-10 of the adrenoleukodystrophy (ALD)
locus of the X chromosome has duplicated to specific locations near the
pericentromeric regions of human chromosomes 2p11,10p11, 16p11 and 22q11.
Comparative sequence analysis reveals 92-96% nucleotide identity,
indicating that the autosomal ALD paralogs arose relatively recently during
the course of higher primate evolution (5-10 million years ago). Analysis
of sequences flanking the duplication region identifies the presence of an
unusual GCTTTTTGC repeat which may be a sequence-specific integration site
for the process of pericentromeric- directed transposition. The breakpoint
sequence and phylogenetic analysis predict a two-step transposition model,
in which a duplication from Xq28 to pericentromeric 2p11 occurred once,
followed by a rapid distribution of a larger duplicon cassette among the
pericentromeric regions. In addition to facilitating more effective
mutation detection among ALD patients, these findings provide further
insight into the molecular basis underlying a pericentromeric-directed
mechanism for non- homologous interchromosomal exchange.
相似文献
10.
Clarke GN; Bourne H; Hill P; Johnston WI; Speirs A; McBain JC; Baker HW 《Human reproduction (Oxford, England)》1997,12(4):722-726
Donor insemination (DI) using cryopreserved semen commenced at The Royal
Women's Hospital in 1976. Over the next 15 years we performed 5953
treatment cycles to achieve 816 pregnancies (13.7% per cycle) and 706 live
births. In-vitro fertilization (IVF) using donor spermatozoa commenced in
1986. Over the next 5 years we performed 303 treatment cycles for 185
couples. Including subsequent transfer of cryopreserved embryos, a total of
33% of couples achieved a successful pregnancy by IVF. Statistical analysis
indicated that, for DI pregnancies, the most important semen variable was
the percentage post-thaw motility, whilst for normal fertilization in IVF
it was the pre-freeze motility. These results may be explained by the
compensatory effects of post-thaw processing of spermatozoa for IVF, but
not for DI in our clinic.
相似文献