全文获取类型
收费全文 | 28626篇 |
免费 | 2092篇 |
国内免费 | 12篇 |
出版年
2023年 | 89篇 |
2022年 | 331篇 |
2021年 | 547篇 |
2020年 | 331篇 |
2019年 | 435篇 |
2018年 | 719篇 |
2017年 | 546篇 |
2016年 | 939篇 |
2015年 | 1494篇 |
2014年 | 1650篇 |
2013年 | 1842篇 |
2012年 | 2431篇 |
2011年 | 2292篇 |
2010年 | 1476篇 |
2009年 | 1235篇 |
2008年 | 1811篇 |
2007年 | 1573篇 |
2006年 | 1401篇 |
2005年 | 1309篇 |
2004年 | 1262篇 |
2003年 | 1039篇 |
2002年 | 1000篇 |
2001年 | 794篇 |
2000年 | 791篇 |
1999年 | 545篇 |
1998年 | 224篇 |
1997年 | 173篇 |
1996年 | 145篇 |
1995年 | 133篇 |
1994年 | 121篇 |
1993年 | 100篇 |
1992年 | 212篇 |
1991年 | 175篇 |
1990年 | 149篇 |
1989年 | 143篇 |
1988年 | 105篇 |
1987年 | 98篇 |
1986年 | 99篇 |
1985年 | 92篇 |
1984年 | 74篇 |
1983年 | 65篇 |
1982年 | 47篇 |
1981年 | 46篇 |
1979年 | 43篇 |
1978年 | 41篇 |
1976年 | 44篇 |
1975年 | 44篇 |
1973年 | 52篇 |
1971年 | 46篇 |
1970年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
Each of SPF chicken (Hi-Line strain, 2-day-old males) was inoculated with 2.5 or 5 x 10(4) oocysts by stomach tube. The oocyst was the medium type of Cryptosporidium previously isolated from Korean chicken origin, and passed in 2-day-old SPF chicken. The patterns of oocyst discharge were monitored daily, and in order to observe the ultrastructure of the developmental stages, the bursa of Fabricius of the chicken was examined by transmission electron microscopy (TEM) on the 12th day postinoculation. The prepatent period for 8 chicken was 5.9 days postinoculation on the average, and the patent period was 12.9 days. The number of oocysts discharged per day for the chicken was reached peak on day 12 postinoculation on the average. A large number of oocysts was found in fecal samples obtained from inoculated chicken on days 8-14 postinoculation. The ultrastructural feature of almost every developmental stage of the medium type from chicken was very similar to that of Cryptosporidium previously isolated from mammalia including human and birds except for the attachment site of C. muris to the mucus cell from mammalia, but dimension of the oocysts from fecal samples of the medium type was different from those of C. meleagridis and mammalia origin. The above results reveal that the medium type of Cryptosporidium of Korean chicken origin is identified as Cryptosporidium baileyi. 相似文献
104.
A case of anisakiasis causing intestinal obstruction 总被引:1,自引:0,他引:1
A 31-year old salesman living in Seoul developed suddenly abdominal pain due to intestinal obstruction. Exploratory laparotomy exhibited segmental jejunal cellulitis caused by penetrating Anisakis larva. The patient had eaten raw fish. The typical history of intestinal anisakiasis was presented with a short review of Korean patients of anisakiasis. 相似文献
105.
Cryptosporidium, a coccidian protozoa, commonly causes a self-limiting diarrheal illness in humans and animals. Fecal samples from various animals in Chonbuk district were observed using Sheather's flotation technique, Kinyoun's modified acid-fast staining, and osmic acid pre-fixed Giemsa staining. The oocysts were detected in 74 cages (29.6%) out of 250 cages of mature mice, 26 (13.3%) out of 195 mature house rats, 75(15.0%) out of 4-week-old 500 fowls, 98(19.9%) out of 6 to 8-month-old 500 pigs, and 111(22.2%) out of 2 to 5-year-old 500 dairy cattle, respectively. The degree of prevalence was slight in general, but actual prevalence was higher than infection rate because the detection rates were higher in repeated-preparation examinations in comparison to the first examination. Meanwhile, large and small types of oocysts were detected from mice, house rats, pigs, and cattle, and medium type from fowls. 相似文献
106.
Martin W. Ganal Meredith W. Bonierbale Marion S. Roeder William D. Park Steven D. Tanksley 《Molecular & general genetics : MGG》1991,225(3):501-509
Summary Genes for the major storage protein of potato, patatin, have been mapped genetically and physically in both the potato and tomato genomes. In potato, all patatin genes detected by the cDNA clone pGM01 map to a single locus at the end of the long arm of chromosome 8. By means of pulsed field gel electrophoresis (PFGE) it was possible further to delimit this locus, containing 10–15 copies of the gene, to a maximum size of 1.4 million base pairs. Hybridizations with class-specific clones suggest that the locus is at least partially divided into domains containing the two major types of patatin genes, class I and II. In tomato, patatin-homologous sequences were found to reside at the orthologous locus at the end of chromosome 8. The approximately three copies in tomato were localized by PFGE to a single fragment of 300 kilobases. Whereas the class II-specific 5 promoter sequences reside in tomato at the same locus as the coding sequences, the single class I-specific copy of the 5 promoter sequences was localized on chromosome 3 with no coding sequence attached to it. A clone from this chromosome 3 locus of tomato was isolated and by restriction fragment length polymorphism mapping it could be further shown that a similar class I-specific sequence also exists on chromosome 3 of potato. As in tomato, this copy on chromosome 3 is not linked to a coding sequence for patatin. The results are discussed with respect to genome evolution and PFGE analysis of complex gene families. 相似文献
107.
A single-stage two-flap method of total ear reconstruction 总被引:2,自引:0,他引:2
A single-stage two-flap method of total ear reconstruction in congenital microtia is reported. This method was derived from the one-stage reconstruction described by Song and Song. Two flaps defined by vascular basis were elevated on the mastoid area: the superficial skin flap supplied mainly by subcutaneous pedicled arteriole perforators from the posterior auricular artery and the deeper axial-pattern fascial flap including the posterior auricular artery itself. The ear framework, exaggeratedly carved using autologous rib cartilage, could be inserted easily between the two flaps, simultaneously producing the auriculocephalic angle and the conchal wall. Intraoperative expansion of the skin flap and postoperative external ear molding also were performed to create aesthetically pleasing ears. 相似文献
108.
Summary A new anionic high molecular weight polysaccharide, Methylan, was produced byMethylobacterium organophilum from methanol as a sole source of carbon and energy under the specific culture conditions. By GPC and light scattering, the molecular weight was determined to be 2–4×106 dalton and the distribution of molecular weight was very homogeneous. Methylan was composed of carbohydrate (80%), uronic acid (12%), protein (6%) and pyruvic acid (5%). The sugar composition of Methylan was identified as glucose, galactose and mannose with the approximate molar ratio of 232. Methylan solution showed a pseudoplastic non-Newtonian fluid property at the concentration above 0.05%. At the concentration of 1% Methylan solution, the consistency index was 18,000 centipoise which was almost 10 times higher than that of Xanthan and the flow behavior index was 0.15. 相似文献
109.
Kyung Hwan Jung Mahn Hoon Park Hong Mo Moon Joon Shick Rhee 《Biotechnology letters》1991,13(12):857-862
Summary In the hepatitis B surface antigen (HBsAg)-producing recombinant yeast culture medium, the supply of Bacto-yeast nitrogen base without amino acids was found to be inadequate due to the lack of the several kinds of vitamins and trace elements. When the culture medium for this recombinant yeast was supplemented with sufficient vitamins and trace elements, its growth, HBsAg production and the stability of plasmid were improved. 相似文献
110.
Young leaves of wheat exhibit a smooth developmental gradient with meristematic cells at the base and highly differentiated cells at the tip. During differentiation, mesophyll cells attain a lobed outline resembling tube-shaped balloons with almost regularly spaced isthmi. Microfilament patterns in developing wheat mesophyll cells were investigated using fluorescent-labeled phalloidin. Various patterns were found, including delicate arrays of transversely oriented microfilaments in the cortex of the cytoplasm. A close correlation between changes in the patterns of cortical microfilaments, microtubules, cell wall microfibrils, and cell shape was observed. The fine arrays of transversely oriented microfilaments coaligned with bands of microtubules occurring during cell elongation. These bands were found beneath sites of intense wall deposition. It has recently been proposed that the resulting hoops of wall reinforcement prevent cell expansion in the corresponding regions and thus give rise to the peculiar cell shape. When cell expansion ceased, and the typical lobed cell shape was attained, a dense network of microfilaments was retained in the cytoplasm, which was in contrast to what has been described for the microtubular arrays. 相似文献