全文获取类型
收费全文 | 579篇 |
免费 | 21篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 3篇 |
2017年 | 10篇 |
2016年 | 16篇 |
2015年 | 22篇 |
2014年 | 22篇 |
2013年 | 26篇 |
2012年 | 27篇 |
2011年 | 35篇 |
2010年 | 14篇 |
2009年 | 15篇 |
2008年 | 33篇 |
2007年 | 31篇 |
2006年 | 25篇 |
2005年 | 22篇 |
2004年 | 20篇 |
2003年 | 37篇 |
2002年 | 27篇 |
2001年 | 9篇 |
2000年 | 21篇 |
1999年 | 23篇 |
1998年 | 13篇 |
1997年 | 6篇 |
1996年 | 15篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有600条查询结果,搜索用时 453 毫秒
511.
512.
Atsuo Nakayama Hiroshi Nagura Toyoharu Yokoi Masafumi Ito Junpei Asai 《Virchows Archiv. B, Cell pathology including molecular pathology》1992,61(1):389-396
The expression of class II major histocompatibility complex (MHC) antigens on alveolar epithelial cells and macrophages was
investigated immunocytochemically in paraquat-induced alveolitis in the rat lung. Until 2 days after paraquat injection, class
II MHC antigens were expressed on the type II alveolar epithelium without any inflammatory cellular infiltration. From the
4th to the 7th day after paraquat injection, class II MHC antigen-positive macrophages increased in the alveolar spaces, whereas
the expression on the type II alveolar epithelium became obscure. Over 10 days after the injection, interstitial fibrosis
progressed and the intra-alveolar inflammatory infiltrates decreased. Epithelial cells lining the thickened fibrous septa
no longer expressed class II MHC antigens. These results suggest that chemical stimuli can induce class II MHC antigen expression
on the type II alveolar epithelium in the early stage of cellular injury, followed by inflammatory infiltration and interstitial
fibrosis. 相似文献
513.
Katsuhiko Yokoi Mieko Kimura Yoshinori Itokawa 《Biological trace element research》1991,31(3):265-279
A technique for the rapid and accurate estimation of nonheme iron using inductively coupled plasma-atomic emission spectrometry is described. Yttrium was used as an internal standard. An external calibration method was used. The standards were prepared in a matrix composed of 2.5N HCl in 10% (w/v) trichloroacetic acid. The supernatant and coagulum fractions of liver nonheme iron were separated by the method of Drysdale and Ramsay with minor modification. The data determined by this procedure was compared and found to be agreement with data determined by the method of Hallgren. To evaluate the iron status of rats, hemoglobin and liver nonheme iron were determined. Hemoglobin and all of the nonheme iron fractions of the rats fed an iron-deficient diet were significantly lower than those of the rats fed an iron-sufficient diet. The blood content in the liver was estimated to be 80 microL/g from the blood iron concentration, and the difference between total and nonheme iron concentration in liver. 相似文献
514.
Hiromichi Yokoi Yoshihiro Tsuruo Tadayuki Miyamoto K. Ishimura 《Histochemistry and cell biology》1998,109(2):127-134
Steroid 5α-reductase in the rat adrenal gland is supposed to play a role in the catabolism of adrenal steroids. We showed
immunohistochemically the cellular and subcellular localization of 5α-reductase in the rat adrenal gland, using a polyclonal
antibody against 5α-reductase rat type 1. In the adrenal cortex, positive immunoreaction was found in the cells of the zonae
fasciculata and reticularis but was absent in those of the zona glomerulosa. The positive staining was restricted to the cytoplasm
but not to the nucleus, Golgi complexes or mitochondria. The staining intensity showed a marked change depending on the steroidal
milieu. Gonadectomy for 6 weeks increased the immunoreaction, regardless of the sex. Testosterone replacement for the last
2 weeks considerably reduced the immunoreaction in 6-week-castrated males, and estradiol supplement for the last 2 weeks also
resulted in the marked reduction of immunostaining in 6-week-gonadectomized females. In the adrenal medulla, the immunoreaction
was localized in the supporting cells and the Schwann cells but not in the chromaffin cells. In these cells, the immunoreaction
was not affected by steroidal treatments. These findings suggest that the expression of 5α-reductase in the rat adrenal cortex
is regulated by sex hormones from the gonads, and the enzyme may participate in the conversion of adrenal steroids depending
on the steroidal environment, although the functional significance of the enzyme in the adrenal medulla remains unclarified.
Accepted: 27 June 1997 相似文献
515.
Stephen P. Ellner Akira Sasaki Yoshihiro Haraguchi Hirotsugu Matsuda 《Journal of mathematical biology》1998,36(5):469-484
We propose a simple approach to approximating the speed of invasion in lattice population models. Approximate critical parameter
values for successful invasion are then found by solving for zero wave speed. The approximation is based on describing the
occupied region by the ordinary pair approximation, and using quasi-steady-state pair approximations to describe the leading
edge of the wave front. We illustrate this idea using the basic contact process on the 1 and 2 dimensional lattice (with and
without nearest-neighbor migration), finding very good agreement between the approximation and simulation results. The approximate
critical values obtained by our approximation are significantly more accurate than those obtained by the ordinary pair approximation.
Received 4 September 1996 相似文献
516.
517.
Functional reconstruction using a depressor anguli oris musculocutaneous flap for large lower lip defects, especially for elderly patients 总被引:1,自引:0,他引:1
Described here is a new technique to reconstruct large lower lip defects using one or two musculocutaneous island flaps, which includes an innervated depressor anguli oris muscle and has a facial artery in its pedicle. Vermilion is simultaneously reconstructed using a mucosal transposition flap. Three patients who had a total lower lip defect and five patients who had a defect larger than one-half of the lower lip were treated by our procedure. All the flaps survived completely without any signs of vascular stasis. In six patients, sphincter function and sensation appeared within 3 months after surgery. In one patient who needed a total lower lip reconstruction, the depressor anguli oris muscle was atrophic and the motor nerve could not be found. This patient could not regain motion. One other patient complained of a sialorrhea accompanied by sensory loss; however, his sensation improved within 6 months after surgery. All of the reconstructed lower lips were large enough to enable the patient to wear dentures and were of a cosmetically acceptable appearance 1 year after surgery. 相似文献
518.
We examined the effect of pretreatment with EPC-K1, a potent hydroxyl radical scavenger, on 6-hydroxydopamine (6-OHDA)-induced reduction of dopamine (DA) and its metabolites in the mouse striatum. EPC-K1 was mixed with diet (0.2%, wt/wt) for 1 or 2 weeks, and then 6-OHDA (60 g in 2l of saline solution) was injected intracereberoventricularly. Mice continued to be fed EPC-K1-containing diet for another one week before they were sacrificed. The concentrations of DA and its metabolites in the striatum were measured by high performance liquid chromatography. 6-OHDA reduced the level of DA and its metabolites in the striatum. Pretreatment with EPC-K1 for 2 weeks, but not for 1 week, abrogated the neurotoxic effect of 6-OHDA on striatal concentrations of DA and its metabolites. Measurement of striatal concentrations of thiobarbituric acid reactive substances, glutathione, and malonaldehyde plus 4-hydroxynonenal, and the activities of superoxide dismutase and catalase in EPC-K1 treated mice showed an increase in catalase activity after 2 weeks of such treatment. No other changes in anti-oxidants levels were noted. Our results suggest that EPC-K1 counteracts the neurotoxicity of 6-OHDA by increasing catalase activities. 相似文献
519.
520.
Kazuya Kobayashi Hirotsugu Ishizu Sachiko Arioka Jocelyn Padilla Cabrera Motonori Hoshi Midori Matsumoto 《Chromosoma》2008,117(3):289-296
Triploidy has generally been considered to be an evolutionary dead end due to problems of chromosomal pairing and segregation during meiosis. Thus, the formation of tetraploids and diploids from triploid types is a rare phenomenon. In the present study, we demonstrated that inbreeding of the triploid planarian Dugesia ryukyuensis resulted in both diploid and triploid offspring in nature. In the triploids of D. ryukyuensis, chiasmata between homologous chromosomes were observed in both female and male germ lines. This result suggests that both diploid and triploid offspring of this species are produced bisexually by zygotic fusion between sperm and eggs. Hence, this phenomenon may be a novel mechanism in planarian for escaping the triploid state. 相似文献