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排序方式: 共有1185条查询结果,搜索用时 31 毫秒
1.
2.
Summary— KR31080 (2-butyl-5-methyl-6-(1-oxopyridin-2-yl)-3-[[2'-(1H-tetrazol-5-yl) biphenyl-4-yl]methyl]-3H-imidazo[4,5-b] pyridine) is a potent inhibitor of angiotensin type 1 (AT1 ) receptors in rabbit aorta and human recombinant AT1 receptors. In the isolated rabbit thoracic aorta, KR31080 caused a nonparallel shift to the right of the concentration-response curves to angiotensin II (All) with decreased maximal response (pD'2 = 10.1 ± 0.1), but had no effect on the contractile response induced by norepinephrine. KR31080 inhibited specific [125 I]AII binding to rabbit aortic membranes (AT, receptors) and [125 I][Sar1 , Ile8 ]AII binding to human recombinant AT1 receptors in a concentration-dependent manner with IC50 values of 0.84 ± 0.08 nM and 1.92 ± 0.15 nM, respectively, but did not inhibit specific [125 I)AII binding to bovine cerebellum membranes (ÀT2 receptors). In the Scatchard analysis, KR31080 interacted with rabbit aortic AT1 receptors in a competitive manner, similar to losartan. These results demonstrate that KR31080 is a potent and AT1 selective angiotensin receptor antagonist which exerts a competitive antagonism in the [125 I]AII binding assay and insurmountable AT1 receptor antagonism in the functional study. 相似文献
3.
Sports anemia. 总被引:13,自引:0,他引:13
E P Balaban 《Clinics in Sports Medicine》1992,11(2):313-325
It is apparent that exercise can influence erythropoiesis and red cell survival in a variety of fascinating ways. A number of mechanisms have been reviewed that could lead to mild changes in the Hb or red cell mean corpuscular volume. In addition, athletes may be at high-risk to develop decreased iron stores. Nevertheless, iron deficiency anemia is uncommon and the ritual of routine iron supplementation is not recommended. Clearly, most of the mechanisms discussed lead to only subtle changes in the overall red cell numbers and indices. Yet there is a small subset of athletes who will have red cell changes that can only be attributable to participation in sports. The diagnosis of sports anemia, however, remains one of exclusion. 相似文献
4.
5.
The steady-state kinetics of the creatine kinase reaction in rabbit skeletal muscle in vivo was investigated using inversion and saturation magnetization transfer techniques. Both techniques determined the forward rate of this reaction (creatine phosphate ATP) as approximately 0.3 s-1. This corresponds to a flux of 10 mumol creatine phosphate/s/g muscle. The saturation transfer technique underestimated the reverse reaction by approximately 56%. This result is likely due to the participation of ATP in other interactions in skeletal muscle not involving creatine phosphate. 相似文献
6.
SUMMARY Elevated plasma levels of Lp(a) do seem to influence the progression of atherosclerosis. Evidence is emerging that certain apo(a) isoforms may be more atherogenic than others, and in transgenic mice free apo(a) has been shown to be associated with accelerated atherosclerosis. Currently it is not known whether treating elevated Lp(a) levels will reduce progression of atherosclerosis and, as therapeutic options are limited, mass screening of Lp(a) levels in populations is not indicated. The presence of raised Lp(a) levels, however, warrants aggressive treatment to reduce other cardiovascular risk factors. Continuing research to investigate the relationship of the apo(a) gene to other genes, including the plasminogen gene and apo(a)-related genes, will add further information pertaining to the evolution, function, regulation and clinical implications of Lp(a). 相似文献
7.
8.
In this study the exchange between 1H magnetization in "free" water (1Hf) and that in a pool with restricted motion (1Hr) was observed in tissues in vivo using NMR saturation transfer methods. Exchange between these two pools was demonstrated by a decrease in the steady-state magnetization and relaxation times of 1Hf with radiofrequency irradiation of 1Hr. The pseudo-first-order rate constant for the movement of magnetization from 1Hf to 1Hr was approximately 1 s-1 in kidney and approximately 3 s-1 in skeletal muscle in vivo. Proton NMR imaging demonstrated that this exchange was tissue specific and generated a novel form of NMR image contrast. The extent of exchange between 1Hf and 1Hr as well as the topological correlation of the exchange with relaxation weighted images suggests that this pathway is a major determinant of the observed relaxation properties of water 1H in vivo. 相似文献
9.
Oocyte morphology does not affect fertilization rate, embryo quality and implantation rate after intracytoplasmic sperm injection 总被引:6,自引:10,他引:6
Balaban B; Urman B; Sertac A; Alatas C; Aksoy S; Mercan R 《Human reproduction (Oxford, England)》1998,13(12):3431-3433
In this study, we compared the fertilization rate and embryo quality after
intracytoplasmic sperm injection (ICSI) as they relate to oocyte
morphology. A total of 654 ICSI cycles yielding 5903 metaphase II oocytes
were observed. The oocytes retrieved in these cycles were divided into (i)
normal oocytes, (ii) oocytes with extracytoplasmic abnormalities (dark zona
pellucida and large perivitelline space), (iii) oocytes with cytoplasmic
abnormalities (dark cytoplasm, granular cytoplasm, and refractile body),
(iv) oocytes with shape abnormalities, and (v) oocytes with more than one
abnormality (double and triple abnormalities). Intracytoplasmic vacuoles
and aggregates of smooth endoplasmic reticulum were not recorded
separately. The fertilization rate and quality of morphologically graded
embryos did not differ between the groups. There were 77 cycles where all
transferred embryos were derived from abnormal oocytes, and 164 cycles
where all embryos were derived from normal oocytes. These cycles were
studied further. The two groups were comparable regarding mean female age,
duration of infertility, duration of ovarian stimulation, number of
ampoules of gonadotrophin injected, and number of oocytes retrieved. Two
clinical pregnancy rates (44.4 versus 42.1%) and implantation rates per
embryo (10.3 versus 13.2%) were similar. In conclusion, in couples
undergoing ICSI, abnormal oocyte morphology is not associated with a
decreased fertilization rate or unfavourable embryo quality. Furthermore,
embryos derived from abnormal oocytes yield similar clinical pregnancy and
implantation rates when transferred compared with embryos derived from
normal oocytes.
相似文献
10.
Detection of chromosomes and estimation of aneuploidy in human spermatozoa using fluorescence in-situ hybridization 总被引:11,自引:0,他引:11
The development and application of fluorescence in-situ hybridization
(FISH) has opened the way for comprehensive studies on numerical chromosome
abnormalities in human spermatozoa. FISH can be rapidly applied to large
numbers of spermatozoa and thus overcomes the major limitation of
karyotyping spermatozoa after penetration of zona-free hamster oocytes. The
simultaneous hybridization of two or more chromosome-specific probes to
spermatozoa and subsequent detection of the bound probes using different
fluorescent detection systems enables two or more chromosomes to be
localized simultaneously in the same spermatozoon and provides a technique
for undertaking reasonable estimates of aneuploidy. The most commonly used
probes are those which bind to the centromeric region of specific
chromosomes. Most studies to date have concentrated on estimating
aneuploidy in spermatozoa from normospermic men, although reports are
beginning to appear on aneuploidy in spermatozoa from subfertile and
infertile men. Multi- probe FISH studies have generally reported disomy
(hyperhaploidy) estimates of 0.05-0.2% per chromosome. There is preliminary
evidence that some chromosomes such as X, Y and 21 are predisposed towards
higher rates of non-disjunction during spermatogenesis. There are also
suggestions of inter-donor variability in aneuploidy frequencies for
specific chromosomes, although this requires confirmation in larger
studies. While FISH is clearly a powerful technique that has many
applications in reproductive medicine, it must also be realized that it
does have limitations and the technology itself is still evolving and has
yet to be fully validated on spermatozoa.
相似文献